Abstract:

Water electrolysis has been regarded as the most promising green hydrogen production technology. The development of highly efficient hydrogen evolution reaction (HER) catalysts is of great significance for its large-scale application. In this study, a series of NiS(x)@NF transition metal sulfide nanosheet catalysts (x represents the amount of thiourea) were prepared by in-situ growth of Ni₃S₄ on nickel foam (NF) with thiourea as sulfur source. The structure, morphology and metal valence of the catalysts were characterized. The HER properties of the catalyst were studied in 1mol/L KOH electrolyte and simulated seawater respectively. The catalyst preparation was by a simple hydrothermal method and directly used the Ni on NF without adding Ni. The method was simple and low-cost, and the active phase of the catalyst was firmly attached onto the NF substrate presenting high stability. Compared with unvulcanized NF, the NiS(x)@NF catalysts presented a significantly improved HER performance in alkaline electrolytes. This could be attributed to the in-situ growth of Ni₃S₄ nanosheets on NF. Among them, the NiS(0.14)@NF catalyst possessed the smallest overpotential (η₁₀=0.091V, η₁₀₀=0.102V) and the highest intrinsic catalytic activity with a Tafel slope of only 105.23mV/dec. The HER activity of the catalyst significantly decreased in the simulated seawater, indicating that the interfering components in the seawater had a significant impact on HER activity. However, it was worth noting that the NiS(0.14)@NF catalyst exhibited high stability in both alkaline solution and simulated seawater under different current loads (10mA/cm², 40mA/cm², and 100mA/cm²). This could also be ascribed to the in-situ growth of Ni₃S₄ nanosheets on NF, which made the active phase NiS(x) firmly attach onto the NF substrate.

Key words: electrochemistry, catalyst, vulcanization of nickel foam (NF), seawater electrolysis, hydrogen evolution reaction (HER) process

摘要：

电解水制氢是最具潜力的绿氢制备技术，而高效析氢反应（HER）催化剂的开发对其大规模推广意义重大。本文以硫脲为硫源，在泡沫镍（NF）上原位生长Ni₃S₄，制备了一系列NiS(x)@NF过渡金属硫化物纳米片催化剂（x代表硫脲用量），对催化剂进行了结构、形貌以及金属价态等表征，并于1mol/L KOH碱液以及模拟海水中研究了催化剂的HER性能。催化剂制备采用简单的水热法，且直接利用NF上的Ni，无需额外加入Ni源，不仅制备方法简单、成本低，且活性相与NF基底结合牢固，稳定性好。HER性能测试结果表明，与NF相比，NiS(x)@NF催化剂在碱性电解液中HER性能得到明显提升，这归因于NF上原位生长Ni₃S₄纳米片。其中，NiS(0.14)@NF催化剂具有最小的过电势（η₁₀=0.091V，η₁₀₀=0.102V）、最高的内在催化活性，且Tafel斜率只有105.23mV/dec。催化剂在模拟海水中的HER活性明显降低，表明海水中的干扰组分对HER活性影响较大。但值得注意的是，在不同的电流负载下（10mA/cm²、40mA/cm² 以及100mA/cm²），NiS(0.14)@NF催化剂在碱液及模拟海水中均显示出了较高的稳定性，这是由于采用原位生长法直接在NF上生长Ni₃S₄，使活性相与NF基底结合牢固，不易脱落的缘故。

关键词: 电化学, 催化剂, 泡沫镍硫化, 海水电解, 析氢反应过程