Wang Yin, Yang Yutong, Wang Xia, Li Peihe, Shao Hongyang, Li Tianen, Liu Haiyang, Zheng Qingfu, Hu Jing, Duan Limei, Hu Changwen, Liu Jinghai
Inner Mongolia Key Laboratory of Carbon Nanomaterials, College of Chemistry and Chemical Engineering, Nano Innovation Institute, Inner Mongolia University for Nationalities Tongliao 028000 China
Key Laboratory of Cluster Science, Ministry of Education of China, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology Beijing 100081 China
Nanoscale Adv. 2020 Jan 6;2(2):792-797. doi: 10.1039/c9na00725c. eCollection 2020 Feb 18.
Constructing noble metal-free electrocatalytically active sites for the simultaneous hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline solution is key to realizing electricity-driven water splitting in practical applications. Here, we rationally designed Co(OH)@CoSe nanorods (NRs) as an excellent bifunctional electrocatalyst by an electrochemical transformation strategy, where the Co-based nanorod template was converted into Co(OH)@CoSe at the cathode. The obtained electrode exhibits superior electrocatalytic activity for both the HER (overpotential of 208 mV at 20 mA cm) and the OER (268 mV at 20 mA cm) at high current density in a 1 M KOH solution. The theoretical calculations and experimental evidence indicate that the chemical coupling Co-OH active site between Co(OH) and CoSe regulates the hydrogen adsorption and desorption energy and fast electron transfer capability, which is responsible for the improved HER. Moreover, the Co(OH)@CoSe NRs can be further converted into CoOOH nanosheets which serve as OER active sites. Toward practical electrolytic cell applications, the Co(OH)@CoSe nanorods as both the cathode and anode achieved a current density of 100 mA cm at 1.94 V for overall water splitting, better than that of noble metal-based electrocatalysts.
构建用于在碱性溶液中同时进行析氢反应（HER）和析氧反应（OER）的无贵金属电催化活性位点是在实际应用中实现电驱动水分解的关键。在此，我们通过电化学转化策略合理设计了Co(OH)@CoSe纳米棒（NRs）作为一种优异的双功能电催化剂，其中Co基纳米棒模板在阴极被转化为Co(OH)@CoSe。所获得的电极在1 M KOH溶液中于高电流密度下对HER（在20 mA cm时过电位为208 mV）和OER（在20 mA cm时为268 mV）均表现出优异的电催化活性。理论计算和实验证据表明，Co(OH)和CoSe之间的化学耦合Co-OH活性位点调节了氢吸附和解吸能量以及快速电子转移能力，这是HER性能提升的原因。此外，Co(OH)@CoSe NRs可以进一步转化为用作OER活性位点的CoOOH纳米片。对于实际的电解池应用，Co(OH)@CoSe纳米棒作为阴极和阳极在1.94 V下实现了100 mA cm的全水分解电流密度，优于基于贵金属的电催化剂。
