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A facile method has been suggested for the preparation of poly [2,2′-(p-oxydiphenylene)-5,5′-benzimidazole] (OPBI) membrane that comprises of dense and porous layers for high temperature proton exchange membrane fuel cells (HT-PEMFCs). The porosity as well as the asymmetry of the membrane is formed by the use of component solvent at steadily increasing temperatures. This approach needs not to use any porogen, whereas the resultant asymmetric OPBI membrane indicates an improved phosphoric acid (PA) doping level together with mechanical strength. For instance, the PA doping level of the asymmetric OPBI membrane is almost twice as much as that of the homogenous dense OPBI membrane. The conductivity of asymmetric OPBI arrived at 0.072 S cm−1 at 180 °C. The membrane electrode assembly (MEA) based on the asymmetric OPBI demonstrated an exceptional fuel cell functionality with a peak power density of 393 mW cm−2 at 160 °C under anhydrous conditions.

Owing to its high wettability and the resulting compatibility with the future industrial device fabrication process, the conjugated polyelectrolyte (CPE) has becoming a promising hole-transporting material (HTM) in the inverted perovskite solar cell (iPSC); however, only a few highly efficient CPEs have been reported probably due to the limited pool of molecular designing strategies. Here we construct a CPE named DTB(Na) with the same main-chain of a polymer DTB(EH) that was previously employed as a dopant-free HTM in a highly efficient regular type PSC (rPSC) and with simple water/alcohol soluble side-chains. Compared with its analog bearing the only variation of less thiophene units in the main-chain, DTB(Na) shows stronger capacities of hole-extraction and defect-passivation, which should be ascribed to the more intensive exposure of thiophene functional unit to the perovskite layer. As a result, the DTB(Na) iPSC device presents enhanced values on all the photovoltaic parameters and long-term stability, and a power conversion efficiency of 19.92% is realized. Our results demonstrate the feasibility for efficient polymeric HTMs in rPSCs and iPSCs to share the same main-chains, thus enriching the molecular designing strategies and probably expanding the library of efficient HTMs for iPSCs.

Metal-Nx-C based materials have emerged as one of the most promising electrocatalysts for electrochemical reduction of carbon dioxide (ERCD). Co-based macrocyclic compounds have shown unique performance, however, of which the relationship between the ligands structure surrounding Co–N4 centers and reaction mechanism remains vague. To explore this issue, here, a series of Co-based macrocyclic compounds are elaborately chosen as model catalysts, including phthalocyanine cobalt (CoPc), cobalt (II) meso-Tetraphenylporphine (CoTp) and cobalt tetramethoxyphenylporphyrin (CoTop), which possess well-defined Co-N4 coordinated centers but different ligands structure surrounding Co-N4. Electrochemical measurements show that CoPc possesses higher activity and selectivity for CO with Faradaic efficiency (FE) above 62% at −0.7 V (vs. RHE) relative to those of CoTp and CoTop. Combining density functional theory (DFT) calculations, it can be further confirmed that CoPc is more favorable for ERCD to CO due to the rapid formation of key intermediate COOH* and the desorption of CO, demonstrating that the structure of ligands (phthalocyanine) surrounding Co-N4 plays a crucial role in the high CO selectivity. It can be anticipated that an exclusive strategy will pave a new avenue for further understanding the ERCD mechanism of Co-Nx-C catalysts.

Due to their unique activity towards formation of alcohols and hydrocarbons, copper (Cu) based catalysts have been widely used in the electrochemical reduction of carbon dioxide (ERCD). Cu foam naturally possesses three-dimensional (3D) porous structure and catalytically active Cu elements, exhibiting very good catalytic ability for ERCD. Herein, nanostructured self-supporting Cu electrodes with Cu foam as the substrate, with progressive morphologies of nanowires (CuNW), nanosheets (CuNS) and nanoflowers (CuNF), are in-situ prepared by simply adjusting the reaction time in a strongly alkaline oxidizing solution. It is found that the performance and products distribution of ERCD are affected by both the morphology of the as prepared nanostructured self-supporting Cu electrodes and the electrolyte species. As electrode micromorphology evolves from nanowire to nanoflower, the initial electrode potential required for C2 products generation shifts to more positive values. The CuNS electrode shows the highest Faradaic efficiency (FE) of 86.9% at −0.4 V (vs. RHE) and superior performance, owing to its nanosheet morphology that can better stabilize the intermediate state products. Moreover, both total FE and products distribution are affected by the electrolyte anion species. The highest total FE in the investigated electrolyte on CuNS electrode obeys the following order: KHCO3 (86.9%, −0.4 V (vs. RHE)) > KCl (54.7%, −0.5 V (vs. RHE)) > KH2PO4 (1.0%, −0.9 V (vs. RHE)). In 1.0 mol L−1 KHCO3, the CuNS electrode shows a very complex products distribution; in 1.0 mol L−1 KCl, the products distribution can be feasibly controlled by the applied potential; while in 1.0 mol−1 L KH2PO4, ERCD is almost totally suppressed by hydrogen evolution reaction (HER). It is the first time that the CuNS electrodes are applied for ERCD with low cost, simple synthesis, easy scale-up and high activity. Combined with the flexible control ability in FE and products distribution, CuNS electrode possesses great potential for the industrial application of ERCD.