MOF derived carbon based nanocomposite materials as efficient electrocatalysts for oxygen reduction and oxygen and hydrogen evolution reactions

The escalating global energy demands and the formidable risks posed by fossil fuels coupled with their rapid depletion have inspired researchers to embark on a quest for sustainable clean energy. Electrochemistry based technologies, e.g., fuel cells, Zn–air batteries or water splitting, are some of the frontrunners of this green energy revolution. The primary concern of such sustainable energy technologies is the efficient conversion and storage of clean energy. Most of these technologies are based on half-cell reactions like oxygen reduction, oxygen and hydrogen evolution reactions, which in turn depend on noble metal based catalysts for their efficient functioning. In order to make such green energy technologies economically viable, the need of the hour is to develop new noble metal free catalysts. Porous carbon, with some assistance from heteroatoms like N or S or earth abundant transition metal or metal oxide nanoparticles, has shown excellent potential in the catalysis of such electrochemical reactions. Metal–organic frameworks (MOFs) containing metal nodes and organic linkers in an ordered morphology with inherent porosity are ideal self-sacrificial templates for such carbon materials. There has been a recent spurt in reports on such MOF-derived carbon based materials as electrocatalysts. In this review, we have presented some of this research work and also discussed the practical reasons behind choosing MOFs for this purpose. Different approaches for synthesizing such carbonaceous materials with unique morphologies and doping, targeted towards superior electrochemical activity, have been documented in this review.

Hetero-atom doped porous carbon materials derived from MOFs are efficient noble metal-free electrocatalysts.     

Bimetal phosphide as high efficiency and stable bifunctional electrocatalysts for hydrogen and oxygen evolution reaction in alkaline solution

The development of low-cost, high-efficiency, and stable bifunctional electrocatalysts for large-scale water electrolysis is very important for the sustainable development of energy. In this paper, the nickel cobalt phosphide (CoNiP) microstructure was prepared by the “in situ growth-ion exchange-phosphating” method. Due to the flake structure and the synergistic effect of the bimetal, the synthesized CoNiP microstructure exhibited high electrocatalytic activity and stability for hydrogen and oxygen evolution in alkaline electrolyte. The optimized CoNiP showed low overpotential of 116 mV at 10 mA cm⁻² for hydrogen evolution reaction and 400 mV at 50 mA cm⁻² for oxygen evolution reaction in KOH solution. In addition, it exhibited long-term stability at a high constant current density of 100 mA cm⁻² for 48 hours at room temperature and for 65 hours at 80 °C without significant degradation. Theoretical results showed that the introduction of Co and P atoms could reduce the reaction barrier and improve the electron transfer ability. This work provides a simple and economical way for the synthesis of electrocatalytic bimetal phosphide catalysts.

The CoNiP structure is prepared by a simple “in situ growth-ion exchange-phosphating” method. The CoNiP-0.15 M shows the excellent HER and OER performance, also it exhibits high stability with high current density at room temperature and 80 °C.     

Nickel foam and stainless steel mesh as electrocatalysts for hydrogen evolution reaction,oxygen evolution reaction and overall water splitting in alkaline media

In this work, several commonly used conductive substrates as electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) under alkaline conditions were studied, including nickel foam (Ni foam), copper foam (Cu foam), nickel mesh (Ni mesh) and stainless steel mesh (SS mesh). Ni foam and SS mesh are demonstrated as high-performance and stable electrocatalysts for HER and OER, respectively. For HER, Ni foam exhibited an overpotential of 0.217 V at a current density of 10 mA cm⁻² with a Tafel slope of 130 mV dec⁻¹, which were larger than that of the commercial Pt/C catalyst, but smaller than that of the other conductive substrates. Meanwhile, the SS mesh showed the best electrocatalytic performance for OER with an overpotential of 0.277 V at a current density of 10 mA cm⁻² and a Tafel slope of 51 mV dec⁻¹. Its electrocatalytic performance not only exceeded those of the other conductive substrates but also the commercial RuO₂ catalyst. Moreover, both Ni foam and SS mesh exhibited high stability during HER and OER, respectively. Furthermore, in the two-electrode system with Ni foam used as the cathode and SS mesh used as the anode, they enable a current density of 10 mA cm⁻² at a small cell voltage of 1.74 V. This value is comparable to or exceeding the values of previously reported electrocatalysts for overall water splitting. In addition, NiO on the surface of Ni foam may be the real active species for HER, NiO and FeO_x on the surface of SS mesh may be the active species for OER. The abundant and commercial availability, long-term stability and low-cost property of nickel foam and stainless steel mesh enable their large-scale practical application in water splitting.

Efficient electrocatalytic overall water splitting is achieved with commercially-available and low-cost nickel foam and stainless steel mesh as cathode and anode electrodes.     

Precursor accumulation on nanocarbons for the synthesis of LaCoO3 nanoparticles as electrocatalysts for oxygen evolution reaction

Oxygen evolution reaction (OER) is a key step in energy storage devices. Lanthanum cobaltite (LaCoO₃) perovskite is an active catalyst for OER in alkaline solutions, and it is expected to be a low-cost alternative to the state-of-the-art catalysts (IrO₂ and RuO₂) because transition metals are abundant and inexpensive. For efficient catalysis with LaCoO₃, nanosized LaCoO₃ with a high surface area is desirable for increasing the number of catalytically active sites. In this study, we developed a novel synthetic route for LaCoO₃ nanoparticles by accumulating the precursor molecules over nanocarbons. This precursor accumulation (PA) method for LaCoO₃ nanoparticle synthesis is simple and involves the following steps: (1) a commercially available carbon powder is soaked in a solution of the nitrate salts of lanthanum and cobalt and (2) the sample is dried and calcined in air. The LaCoO₃ nanoparticles prepared by the PA method have a high specific surface area (12 m² g⁻¹), comparable to that of conventional LaCoO₃ nanoparticles. The morphology of the LaCoO₃ nanoparticles is affected by the nanocarbon type, and LaCoO₃ nanoparticles with diameters of less than 100 nm were obtained when carbon black (Ketjen black) was used as the support. Further, the sulfur impurities in nanocarbons significantly influence the formation of the perovskite structure. The prepared LaCoO₃ nanoparticles show excellent OER activity owing to their high surface area and perovskite structure. The Tafel slope of these LaCoO₃ nanoparticles is as low as that of the previously reported active LaCoO₃ catalyst. The results strongly suggest that the PA method provides nanosized LaCoO₃ without requiring the precise control of chemical reactions, harsh conditions, and/or special apparatus, indicating that it is promising for producing active OER catalysts at a large scale.

A simple synthetic process for LaCoO₃ nanoparticles based on the accumulation of precursors on nanocarbon supports was presented. The LaCoO₃ nanoparticles showed excellent OER activity owing to their high surface area and perovskite structure.     

Ru catalyst supported on nitrogen-doped nanotubes as high efficiency electrocatalysts for hydrogen evolution in alkaline media

Due to the potential application in the future energy conversion system, there is an increasing demand for efficient, stable and cheap platinum-free catalysts for hydrogen evolution. However, it is still a great challenge to develop electrocatalysts with high activity similar to platinum or even higher, especially those that can work under alkaline conditions. Ruthenium (Ru), as a cheap substitute for platinum, has been studied as a feasible substitute for (HER) catalyst for hydrogen evolution reaction. In this paper, we designed and developed a novel Ru catalyst (Ru@CNT) supported on nitrogen-doped carbon nanotubes. Electrochemical tests show that even under alkaline conditions (1 M KOH), Ru@CNT still shows excellent catalytic performance and good durability. It only needs 36.69 mV overpotential to reach a current density of 10 mA cm⁻², and its Tafel slope is 28.82 mV dec⁻¹. The catalytic performance of the catalyst is comparable to that of 20% Pt/C. The significant activity is mainly attributed to the chelation of highly dispersed ruthenium atoms on nitrogen-doped carbon nanotubes. Secondly, the one-dimensional pore structures supported by nitrogen heterocarbon nanotubes can provide more opportunities for active centers. Excellent HER performance makes Ru@CNT electrocatalyst have a broad application prospect in practical hydrogen production.

Due to the potential application in the future energy conversion system, there is an increasing demand for efficient, stable and cheap platinum-free catalysts for hydrogen evolution.     

Three-dimensional reduced graphene oxide decorated with cobalt metaphosphate as high cost-efficiency electrocatalysts for the hydrogen evolution reaction

The development of cost-effective non-noble metal electrocatalysts is critical for the research of renewable energy. Transition metal cobalt metaphosphate-based materials have the potential to replace the noble metal Pt. Hence, in this work, we synthesize three-dimensional graphene-supported cobalt metaphosphate (Co(PO₃)₂-3D RGO) for the first time through the one-step hydrothermal synthesis method at low temperature with the aid of PH₃ phosphating. In a 0.5 mol L⁻¹ H₂SO₄ solution, the obtained electrocatalyst exhibits excellent electrochemical activity for the hydrogen evolution reaction (HER) with a small overpotential of 176 mV at a current density of 10 mA cm⁻² and a Tafel slope of 63 mV dec⁻¹. Additionally, in a 1 mol L⁻¹ KOH solution, the electrocatalyst also shows outstanding HER activity with a small overpotential of 158 mV at a current density of 10 mA cm⁻² and a Tafel slope of 88 mV dec⁻¹. Co(PO₃)₂-3D RGO can maintain its catalytic activity for at least ten hours whether in acid or alkali. This work not only demonstrates an excellent electrocatalyst for the hydrogen evolution reaction, but also provides an extremely convenient preparation technology, which provides a new strategy for the development and utilization of high-performance electrocatalysts.

The development of cost-effective non-noble metal electrocatalysts is critical for the research of renewable energy.     

Polydopamine-coated graphene nanosheets as efficient electrocatalysts for oxygen reduction reaction

Polydopamine-modified graphene (G-PDA) materials were synthesized by in situ polymerization of a dopamine monomer on the surface of graphene oxide. X-ray photoelectron spectroscopy (XPS) has confirmed that new N-containing functional groups are formed during the synthesis process, which result in the excellent electrocatalytic activity of the composite towards ORR in terms of onset potential, number of electron transferred and limiting current density. The electrocatalytic activity of the optimized G-PDA sample is better than N-doped graphene and comparable to the commercial 20 wt% Pt/C catalyst. Furthermore, compared with the Pt-based catalysts, the G-PDA showed superior stability and methanol resistance, which favored its practical applications in fuel cells.

Polydopamine-coated graphene nanosheets show excellent electrocatalytic activity towards oxygen reduction reaction.     

2D TiVCTx layered nanosheets grown on nickel foam as highly efficient electrocatalysts for the hydrogen evolution reaction

Exploring highly efficient and durable catalysts for the hydrogen evolution reaction (HER) is crucial for the hydrogen economy and environmental protection issues. Numerous studies have now found that transition metal carbide MXenes are ideal candidates as catalysts for the hydrogen evolution reaction. However, MXenes are inclined to easily undergo lamellar structure agglomeration and stacking, which impedes their further applications. Besides, most of the extant research has focused on single transition metal carbides, and the investigation of double transition metal carbide MXenes is rather rare. In this research work, a three-dimensional (3D) TiVCT_x-based conductive electrode was constructed by depositing 2D TiVCT_x nanosheets on 3D network structured nickel foam (NF) to synthesize a hybrid electrode material (abbreviated as TiVCT_x@NF). TiVCT_x@NF exhibits efficient electrochemical properties with a low overpotential of 151 mV at 10 mA cm⁻² and a small Tafel slope of 116 mV dec⁻¹. Benefitting from the open layer structure and strong interfacial coupling effect, compared to the pristine structure, the resulting TiVCT_x@NF has greatly increased active sites for the hydrogen evolution reaction (HER) and encounters less resistance for charge transfer. In addition, TiVCT_x@NF exhibits better stability in long-term acidic electrolytes. This work provides a tactic to prepare three-dimensional network electrode materials and broadens the application of single transition metal carbide MXenes as water splitting electrodes in the HER, which is beneficial to the application of noble metal-free electrocatalysts.

The TiVCT_x MXene was obtained by etching and peeling methods, and the TiVCT_x@NF hybrid electrode material was obtained by the deposition method. The electrochemical performance was evaluated using a variety of characterization methods.     

Heteroatom-doped nanoporous carbon from recyclable Pueraria lobata and its dual activities for oxygen reduction and hydrogen evolution reactions

Many efficient and non-precious metal catalysts for oxygen reduction or hydrogen evolution reactions have been developed, but bifunctional catalysts for both oxygen reduction reaction and hydrogen evolution reactions are seldom reported despite their advantages. Herein, we designed the bulk preparation of heteroatom-doped nanoporous carbon catalysts using widely available and recyclable Pueraria lobata powder as the carbon source. The typical product was N, P and Fe Tri-doped nano-porous carbon (N,P,Fe-NPC) with high surface area (BET surface area of 776.68 m² g⁻¹ and electrochemical surface area of 55.0 mF cm⁻²). The typical N,P,Fe-NPC sample simultaneously exhibited high activities for oxygen reduction and hydrogen evolution reactions. Because of the high surface area and the tri-doping of N, P and Fe elements, the prepared material may have applications in other fields such as gas uptake, sensors, sewage treatment, and supercapacitors. The suggested approach is low-cost, simple and readily scalable.

The bulk preparation of an N, P and Fe Tri-doped nano-porous carbon sample using recyclable Pueraria powder, which exhibits dual activities.     

Rosette-like MoS2 nanoflowers as highly active and stable electrodes for hydrogen evolution reactions and supercapacitors

MoS₂ is regarded as one of the cost-effective materials for many important applications. In this work, we report a simple one-step hydrothermal method for the directed synthesis of a rosette-like MoS₂ nanoflower modified electrode without using adhesion agents. Interestingly, owing to the hierarchical structures, the as-prepared MoS₂-based electrode exhibits significantly enhanced performance for both the hydrogen evolution reaction in acidic environments and supercapacitors. When used in the hydrogen evolution reaction, the electrode shows a low overpotential of ∼0.25 V at 10 mA cm⁻², a Tafel slope of ∼71.2 mV per decade, and long-term durability over 20 h of hydrogen evolution reaction operation at 10 mV cm⁻². In addition, as a supercapacitor electrode, it exhibits a good capacity of 137 mF cm⁻² at a current density of 10 mA cm⁻² and excellent stability in 1 M H₂SO₄ at a scan rate of 50 mV s⁻¹. The outstanding performances of the as-prepared materials may be ascribed to the unique 3D architectures of the rosette-like MoS₂ nanoflowers. This work could provide a strategy to explore low-cost and highly efficient electrocatalysts with desired nanostructures for the hydrogen evolution reaction and supercapacitors applications.

A simple strategy to synthesize interlayer spacing-enlarged rosette-like MoS₂ nanoflowers for both the hydrogen evolution reaction and supercapacitive energy storage.     

Rapid large-scale synthesis of ultrathin NiFe-layered double hydroxide nanosheets with tunable structures as robust oxygen evolution electrocatalysts

Transition metal layered double hydroxides (LDHs) with ultrathin two-dimensional (2D) structures, especially NiFe-based LDH nanosheets, have been extensively developed as advanced oxygen evolution reaction (OER) electrocatalysts for water splitting. Nevertheless, traditional synthetic approaches for these promising catalysts usually involve tedious pretreatment procedures and a subsequent time-consuming exfoliation process, and the obtained products possess a wide dispersion of thickness and limited production yield. Here, a sequence of ultrathin NiFe-LDH nanosheets with tunable components were prepared on a large scale via a rapid room-temperature method under ambient conditions, and were further used as a desired material model for studying the influence of Ni/Fe ratio modulation on the OER performance. Due to the synergetic effect of more exposed active sites, efficient electron transport and optimized OER kinetics, the resulting LDH samples manifest outstanding electrocatalytic performance toward water oxidation.

A sequence of ultrathin NiFe-LDH nanosheets with tunable components were prepared via a rapid room-temperature method, which were further used as efficient electrocatalysts for water oxidation.     

Platinum nanoparticles on defect-rich nitrogen-doped hollow carbon as an efficient electrocatalyst for hydrogen evolution reactions

Design and synthesis of efficient electrocatalysts with low usage of precious metal and of high stability are essential for their practical applications in hydrogen evolution reactions. In this work, we synthesize an electrocatalyst through the deposition of platinum nanoparticles on defect-rich nitrogen-doped hollow carbon derived from surface-attached poly(4-vinylpyridine) monolayers. The platinum nanoparticles with an average diameter of about 1.8 nm are well dispersed on the outer surface of the pre-synthesized carbon material and the platinum loading is about 8.6 wt%. The mass activity of the as-synthesized catalyst under an overpotential of 55 mV is about 5.0 A mg_Pt⁻¹, about 4.93 times higher than that of commercial Pt/C catalysts. Moreover, the synthesized catalyst is also more electrochemically stable than commercial Pt/C catalysts as evidenced by continuous cyclic voltammetry and chronoamperometric response measurements.

Design and synthesis of efficient electrocatalysts with low usage of precious metal and of high stability are essential for hydrogen evolution reaction in their practical applications.     

Controllable synthesis of N-doped carbon nanohorns: tip from closed to half-closed,used as efficient electrocatalysts for oxygen evolution reaction

The development of efficient, cost-effective and stable N-doped carbon material with catalytic activity as an excellent catalyst for the oxygen evolution reaction (OER) is critical for renewable energy systems. In this study, the unique tip-half-closed N-doped carbon nanohorns (THC-N-CNHs) were firstly produced by the positive pressure-assisted arc discharge method using N₂ as the nitrogen source. Benefitting from the novel tip-half-closed structure and sufficient porosity, the specific surface area (SSA) of THC-N-CNHs is calculated to be 670 m² g⁻¹ without any further treatment, which is three times larger than that of traditional tip-closed CNHs. More importantly, the content of nitrogen can achieve ∼1.98 at% with noticeable pyridinic-N enrichment, increasing the number of active sites for the OER. Furthermore, the three-dimensional spherical feature and the unique pore structure for THC-N-CNHs lead to the fast transportation of electrons, and facile release of the evolved O₂ bubbles during the OER process. Therefore, THC-N-CNHs exhibit excellent electrocatalytic activity toward the OER, with an overpotential of 328 mV at 10 mA cm⁻², which is superior to that of most N-doped carbon material-based electrocatalysts. Meanwhile, the resulting catalyst also shows excellent durability after long-term cycling. Finally, we emphasize that THC-N-CNHs can be promising candidates as cheap, industrially scalable catalytic scaffolds for OER application.

The unique tip-half-closed N-doped carbon nanohorns were firstly produced with sufficient porosity and noticeable pyridinic-N, exhibiting excellent OER performance.     

Controlled synthesis of trimetallic nitrogen-incorporated CoNiFe layered double hydroxide electrocatalysts for boosting the oxygen evolution reaction

The development of non-precious trimetallic electrocatalysts exhibiting high activity and stability is a promising strategy for fabricating efficient electrocatalysts for the oxygen evolution reaction (OER). In this study, trimetallic nitrogen-incorporated CoNiFe (N–CoNiFe) was produced to solve the low OER efficiency using a facile co-precipitation method in the presence of ethanolamine (EA) ligands. A series of CoNiFe catalysts at different EA concentrations were also investigated to determine the effects of the ligand in the co-precipitation of a trimetallic system. The introduction of an optimized EA concentration (20 mM) improved the electrocatalytic performance of N–CoNiFe dramatically, with an overpotential of 318 mV at 10 mA cm⁻² in 1.0 M KOH and a Tafel slope of 72.2 mV dec⁻¹. In addition, N–CoNiFe shows high durability in the OER process with little change in the overpotential (ca. 16.0 mV) at 10 mA cm⁻² after 2000 cycles, which was smaller than that for commercial Ir/C (38.0 mV).

A trimetallic nitrogen-incorporated CoNiFe exhibited good catalytic properties toward the oxygen evolution reaction, e.g., high stability and low overpotential (318 mV at 10 mA cm⁻²).     

Hierarchical NiCo2O4/NiFe/Pt heterostructures supported on nickel foam as bifunctional electrocatalysts for efficient oxygen/hydrogen production

As the demand for clean and renewable energy increases, high-efficiency multifunctional electrocatalysts for water cracking have become a research hotspot. In this study, a NiCo₂O₄/NiFe/Pt composite with a hierarchical structure was successfully constructed by combining a hydrothermal growth and electrodeposition method with nickel foam as the scaffold material, and its overall water cracking reaction was studied. The laminar-structured NiCo₂O₄/NiFe composite exhibits an improved number of electrochemically active sites and shorter electron transport pathways, while the Pt particles deposited on the NiCo₂O₄/NiFe composite are conducive to improve the hydrogen evolution reaction without affecting the efficiency of the oxygen evolution reaction of the intrinsic material. The NiCo₂O₄/NiFe/Pt composite shows an excellent overall water cracking performance under alkaline conditions with a current density of 10 mA cm⁻² at an applied potential of 1.45 V, indicating a promising research prospect.

(a) LSV of overall water splitting for the respective component at a scan rate of 5 mV s⁻¹. (b) Chronopotentiometry curve under a constant current density of 20 mA cm⁻². Inset: photographic image of two-electrode water electrolysis device.     

N-doped mixed Co,Ni-oxides with petal structure as effective catalysts for hydrogen and oxygen evolution by water splitting

Developing electrocatalytic nanomaterials for green H₂ energy is inseparable from the exploration of novel materials and internal mechanisms for catalytic enhancement. In this work, nano-petal N-doped bi-metal (Ni, Co) and bi-valence (+2, +3) (Ni_1−xCo_x)²⁺Co₂³⁺O₄ compounds have been in situ grown on the surface of Ni foam. The N³⁻ atoms originate from the amino group in urea and doped in the compound during annealing. The as-synthesized N-doped (Ni_1−xCo_x)²⁺Co₂³⁺O₄ nano-petals demonstrate commendable hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) bi-functional catalytic efficiency and stability. Electrochemical measurements confirm that the nitrogen doping significantly improves the catalytic kinetics and the surface area. Density functional theory calculations reveal that the improved HER and OER kinetics is not only due to the synergistic effect of bi-metal and bi-valence, as well as the introduction of defects such as oxygen vacancies, but also it more depends on the shortened bond length between the nitrogen N³⁻ atoms and the metal atoms, and the increased electron density of the metal atoms attached to the N³⁻ atoms. In other words, the change of lattice parameters caused by nitrogen doping is more conducive to the catalytic enhancement than the synergistic effect brought by bi-metal. This study provides an experimental and theoretical reference for the design of bi-functional electrocatalytic nanomaterials.

Developing electrocatalytic nanomaterials for green H₂ energy is inseparable from the exploration of novel materials and internal mechanisms for catalytic enhancement.     

Electrochemical oxidation of boron-doped nickel–iron layered double hydroxide for facile charge transfer in oxygen evolution electrocatalysts

The oxygen evolution reaction (OER) is the key reaction in water splitting systems, but compared with the hydrogen evolution reaction (HER), the OER exhibits slow reaction kinetics. In this work, boron doping into nickel–iron layered double hydroxide (NiFe LDH) was evaluated for the enhancement of OER electrocatalytic activity. To fabricate boron-doped NiFe LDH (B:NiFe LDH), gaseous boronization, a gas–solid reaction between boron gas and NiFe LDH, was conducted at a relatively low temperature. Subsequently, catalyst activation was performed through electrochemical oxidation for maximization of boron doping and improved OER performance. As a result, it was possible to obtain a remarkably reduced overpotential of 229 mV at 10 mA cm⁻² compared to that of pristine NiFe LDH (315 mV) due to the effect of facile charge-transfer resistance by boron doping and improved active sites by electrochemical oxidation.

An electrochemically oxidized boron-doped NiFe LDH electrocatalyst was prepared and the electrocatalyst showed improved water oxidation performance.     

Strategies to improve electrocatalytic performance of MoS2-based catalysts for hydrogen evolution reactions

Electrocatalytic hydrogen evolution reactions (HERs) are a key process for hydrogen production for clean energy applications. HERs have unique advantages in terms of energy efficiency and product separation compared to other methods. Molybdenum disulfide (MoS₂) has attracted extensive attention as a potential HER catalyst because of its high electrocatalytic activity. However, the HER performance of MoS₂ needs to be improved to make it competitive with conventional Pt-based catalysts. Herein, we summarize three typical strategies for promoting the HER performance, i.e., defect engineering, heterostructure formation, and heteroatom doping. We also summarize the computational density functional theory (DFT) methods used to obtain insight that can guide the construction of MoS₂-based materials. Additionally, the challenges and prospects of MoS₂-based catalysts for the HER have also been discussed.

In this review, we summarize three general classes of effective strategies to enhance the HER activity of MoS₂ and DFT calculation methods, i.e. defect engineering, heterostructure formation, and heteroatom doping.     

Recent advances in the metal–organic framework-based electrocatalysts for the hydrogen evolution reaction in water splitting: a review

Water splitting is an important technology for alternative and sustainable energy storage, and a way for the production of hydrogen without generating pollution. In recent years, metal–organic frameworks (MOFs) have become the most capable multifunctional resources because of their high surface areas, tunable porosity, simple modification of compositions, and potential for use as precursors with a variety of morphological structures. Based on these qualities, many MOFs and their derived materials are utilized as electrocatalysts for the water splitting reaction. Herein, we assembled the relevant literature in recent years about MOF and MOF-derived materials for their eminent electrocatalytic activity in water splitting with useful strategies for the design and preparation of catalysts, along with challenges. This review summarizes the advancement in MOF materials, elucidating different strategies for its role in water splitting.

Water splitting is an important technology for alternative and sustainable energy storage, and a way for the production of hydrogen without generating pollution.