Electrochemical sensor formed from poly(3,4-ethylenedioxyselenophene) and nitrogen-doped graphene composite for dopamine detection

In this study, an electrochemical sensor for dopamine (DA) detection has been developed by a composite of poly(3,4-ethylenedioxyselenophene) (PEDOS) and nitrogen-doped graphene (PEDOS/N-Gr) using an in situ polymerization method. Its structure and properties were then compared with those of the composites of poly(3,4-ethylenedioxythiophene) (PEDOT)/nitrogen-doped graphene (PEDOT/N-Gr), which were prepared by the same methods. FT-IR, Raman, UV-vis, XPS, mapping and SEM investigated the structure and morphology of these composites. These revealed that PEDOS/N-Gr had a higher conjugation degree than PEDOT/N-Gr. The synergetic effect between PEDOS and N-Gr was beneficial for the formation of a homogenous surface coating. The cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods were conducted for electrochemical detection of DA. Compared with PEDOT/N-Gr, the PEDOS/N-Gr displayed an enhanced sensitivity and electrocatalytic performance for DA detection with linear ranges of 0.008–80 μM (PEDOT/N-Gr: 0.04–70 μM) and limits of detection (LOD) of 0.0066 μM (S/N = 3) (PEDOT/N-Gr: 0.018 μM (S/N = 3)).

An electrochemical sensor for dopamine detection has been fabricated using a composite of PEDOS and N-Gr. The results of actual samples showed that the composite of PEDOS/N-Gr has excellent recovery (95.40–100.14%) for human serum and urine samples.     

Electrochemical synthesis of hydroxyl group-functionalized PProDOT/ZnO for an ultraviolet photodetector

Ultraviolet (UV) detectors based on zinc oxide (ZnO) nanorods (NRs) are ideal materials for UV radiation detection. However, owing to the surface effect of ZnO NRs, their speed of photoresponse and photosensitivity need to be improved. In this study, a UV photodetector was fabricated via electrochemical coating of poly(3,4-propylenedioxythiophene) grafted with functional groups (–OH) on a hydrothermally grown ZnO NRs. For comparison, poly(3,4-propylenedioxythiophene)/ZnO composites were synthesized using the same method. The structure of the composite film was characterized by Fourier transform infrared spectroscopy (FT-IR), UV-visible spectroscopy (UV-vis), X-ray diffraction (XRD), Raman spectroscopy (Raman), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The effect of the polymer structure on the UV sensing ability of ZnO NRs was evaluated by fabricating a UV detector with a composite material. The structural results indicated that the PProDOT-type conductive polymer and ZnO composites were successfully synthesized. The UV photodetection results showed that the presence of functional groups (–OH) in polymer chains could enhance the responsivity of the material. The response time of the ZnO/PProDOT–OH composite was 15 s shorter than that of the ZnO/PProDOT composite. A rise in photocurrent induced an increase from 2.5 A W⁻¹ to 34.75 A W⁻¹ in the UV photoresponsivity of the ZnO/PProDOT–OH composite, compared with that of the pure ZnO NRs. The external quantum efficiency and detectivity significantly improved, the increases of which were attributed to the coupling of the polymer and ZnO NRs.

Ultraviolet (UV) detectors based on zinc oxide (ZnO) nanorods (NRs) are ideal materials for UV radiation detection.     

Direct deposition of Sn-doped CsPbBr3 perovskite for efficient solar cell application

All inorganic carbon-based planar perovskites, particularly CsPbBr₃, have attracted considerable attention due to their excellent stability against oxygen, moisture, and heat for photovoltaic utilization. However, the power conversion efficiency of carbon-based planar CsPbBr₃ perovskite solar cells is mostly low, primarily because of the inferior film quality with undesirable crystallization and narrow light absorbance ranges. Herein, we develop a novel direct deposition approach combined with Sn doping to achieve highly efficient and stable carbon-based Sn-doped CsPbBr₃ perovskite solar cells. Mass-scale Sn ion-doped CsPbBr₃ perovskite powder was effectively synthesized and characterized via a facile strategy by adding hydrohalic acid in the CsBr, PbBr₂ and SnBr₂ precursor in a dimethyl sulfoxide solution. Moreover, using the as-synthesized CsPbBr₃ and Sn-doped CsPbBr₃ perovskite powder, PSCs were obtained via effective direct thermal evaporation. A smooth, constant and pinhole-free perovskite film was achieved with a configuration of FTO/TiO₂/Sn:CsPbBr₃/carbon. PSCs based on Sn:CsPbBr₃ as an absorber and carbon as the HTM achieved an impressive power conversion efficiency of 8.95% compared to 6.87% for undoped CsPbBr₃; moreover, it displayed admirable stability in an open-air atmosphere for an operational period of about 720 h without a noticeable negative result. The introduction of the Sn ion may advance the interface extraction of charge between the electric transport layer to the absorber layer and absorber to the carbon electrode. Accordingly, the Sn ion doping on CsPbBr₃ during the synthesis phase and the direct evaporation paves a novel approach for intended photovoltaic applications.

All inorganic carbon-based planar perovskites, particularly CsPbBr₃, have attracted considerable attention due to their excellent stability against oxygen, moisture, and heat for photovoltaic utilization.     

Long-term survival outcome of locally advanced gastric cancer patients who achieved a pathological complete response to neoadjuvant chemotherapy

International Journal of Clinical Oncology - Long-term outcome of patients with locally advanced gastric cancer (LAGC) who achieved a pathological complete response (pCR) was scarcely discussed,...