室温合成非晶三硫化钼析氢催化剂的性能调制以及其在串联制氢器件中的应用

高催化活性、低成本、良好工艺兼容性以及高稳定性的析氢催化剂是实现一体化光电化学水解制氢器件的关键, 然而传统的贵金属催化剂由于储量稀缺、成本高昂而严重限制了光电化学水解制氢器件的产业化进程. 本文在室温下通过湿法化学合成法制备了高催化活性、成本低廉以及工艺兼容性好的非金属非晶三硫化钼析氢催化剂, 并研究了不同催化剂滴涂量对其催化活性以及串联制氢器件制氢性能的影响. 结果表明, 存在最优化非晶三硫化钼催化剂滴涂量以获得最佳催化活性(10 mA/cm²电流密度对应电势达260 mV vs. RHE(可逆氢电极), 塔菲尔斜率达68 mV/dec), 其粗糙表面以及多孔结构可获得更大的电化学接触面积以促进析氢反应. 进一步将其作为光阴极应用于串联制氢器件, 可有效降低过电势损失和提高光生电流密度输出, 与光阳极结合有望提高制氢效率.

Modulating catalytic capacities of room-temperature synthetized amorphous molybdenum trisulfide hydrogen evolving catalysts and their applications to in series solar water splitting devices in series

Highly-catalytic, cost-effective, well process-compatible, and highly-stable hydrogen-evolving catalysts are increasingly becoming key catalysts in realizing monolithic electrochemical solar water-splitting devices. However, the typical noble metallic catalysts seriously restrict the industrialization of electrochemical solar water-splitting devices on account of their poor storages and high costs. Low-cost, high-catalytic and non-metallic catalysts pave the promising way for the industrialization process. Molybdenum sulfide has emerged as a type of potential catalyst with high-activity and stability for the hydrogen-evolving reaction (HER) in the acidic condition, nowadays gradually becoming a research hotspot in solar-water-splitting. The process preparation of high-efficient molybdenum sulfide catalyst is consequently extremely important for enhancing the solar-to-hydrogen efficiency. In this paper, we synthesize highly-catalytic, low-cost, and highly-compatible non-metallic amorphous molybdenum trisulfide catalyst based on a simple wet chemical approach at room temperature for hydrogen-evolving reaction, followed by extensive studies of the effects of the mass loading of catalyst on the catalytic capacity and the solar-to-hydrogen performance of solar-water-splitting devices in series. When the mass loading is 0.5 mg·cm^-2, the MoS₃ catalyst exhibits the promising HER activity. the surface of catalyst appears to be rough, porous, nano-sized architecture and the thickness is around 2.0 μm, which simultaneously enlarges the electrochemically active area and reduces charge transfer impedance, accelerating the electron transport to electrochemically active site and improving the interfacial charge transfer. Besides, the HER catalytic activity is illustrated in a wired solar-water-splitting device. The current density can achieve the maximum values of 7.51 and 3.28 mA/cm² corresponding to 0 and 0.8 V vs. RHE, and the onset potential is 1.83 V, comparable to the open circuit voltage (1.90 V) of two amorphous silcon cells in series. Therefore, we conclude that for amorphous molybdenum trisulfide catalyst there exists an optimized mass loading, with which an optimized catalytic capacity (260 mV vs. RHE at 10 mA/cm² and tafel slope of 68 mV/dec) can be achieved. Further, by using the catalyst as a cathode for the solar-water-splitting devices in series, the catalyst can efficiently reduce the overpotential and improve the current output for the device, thereby potentially achieving a higher solar-to-hydrogen efficiency.