School of Medicine and Health, Harbin Institute of Technology, No. 92 West Dazhi Street, Nan Gang District, Harbin 150001, People's Republic of China; Key Laboratory of Microsystems and Microstructures Manufacturing, Harbin Institute of Technology, No.2 Yikuang Street, Nan Gang District, Harbin 150080, People's Republic of China.
School of Chemistry and Chemical Engineering, Harbin Institute of Technology, No. 92 West Dazhi Street, Nan Gang District, Harbin 150001, People's Republic of China.
J Colloid Interface Sci. 2023 Jan;629(Pt A):297-309. doi: 10.1016/j.jcis.2022.08.145. Epub 2022 Aug 27.
It is urgent to develop non-noble metal electrocatalysts with both excellent activity and durable stability for H production via water electrolysis. Electric energy is mainly consumed by the sluggish anodic oxygen evolution reaction (OER). The electrocatalytic urea oxidation reaction (UOR) has been regarded as a promising reaction to replace OER because of its small thermodynamic oxidation potential. However, developing a facile and large-scale preparation method for bifunctional hydrogen evolution reaction (HER) and UOR electrocatalysts is still challenging. Herein, phosphate-modified (4.46 atomic%) NiMoO net-like nanostructures are formed on Ni foam (NF) via HPMoO etching strategy at room temperature (denoted as NF/P-NiMoO). The etched NF can directly serve as HER electrode, and delivers overpotential of 116 mV at current density of 10 mA/cm with Tafel slope of 77.5 mV/dec. Furthermore, it displays excellent UOR activity with potential of 1.359 V at current density of 10 mA/cm and Tafel slope of 19.3 mV/dec. The apparent activation energy of NF/P-NiMoO is 20.6 kJ/mol, lower than that of NF (37.7 kJ/mol), indicating smaller apparent barrier for CN bond cleavage in urea. The cell voltage of urea electrolysis is around 1.48 V for H production to deliver current density of 10 mA/cm, and better long-term stability for 50 h than that of Ir/C||Pt/C. The etching solution can be recycled for five times by addition of HO, turning heteropoly blue into its original state. This work develops a facile and large-scale method to prepare bifunctional HER and UOR electrocatalysts for H production in a less-energy saving way via urea electrolysis.
开发具有优异活性和持久稳定性的非贵金属电催化剂对于通过水电解生产氢气至关重要。电能主要消耗于缓慢的阳极析氧反应（OER）。电催化尿素氧化反应（UOR）由于其较小的热力学氧化电势，已被认为是一种很有前途的反应来替代 OER。然而，开发简便且大规模制备双功能析氢反应（HER）和 UOR 电催化剂的方法仍然具有挑战性。在此，通过室温下 HPMoO 刻蚀策略在 NF 上形成了磷酸盐修饰的（4.46 个原子%）NiMoO 网状纳米结构（表示为 NF/P-NiMoO）。刻蚀后的 NF 可直接用作 HER 电极，在 10 mA/cm 的电流密度下过电势为 116 mV，塔菲尔斜率为 77.5 mV/dec。此外，它在 10 mA/cm 的电流密度下表现出优异的 UOR 活性，电位为 1.359 V，塔菲尔斜率为 19.3 mV/dec。NF/P-NiMoO 的表观活化能为 20.6 kJ/mol，低于 NF（37.7 kJ/mol），表明在尿素中 CN 键断裂的表观势垒更小。用于生产氢气的尿素电解槽的电压约为 1.48 V，电流密度为 10 mA/cm，其稳定性优于 Ir/C||Pt/C，可稳定运行 50 h。通过添加 HO，刻蚀溶液可循环使用五次，将杂多蓝转化为其原始状态。这项工作开发了一种简便且大规模的方法，通过尿素电解以节能的方式制备双功能 HER 和 UOR 电催化剂用于生产氢气。
