Li Haoquan, Chen Long, Jin Pengfei, Lv Heng, Fu Haihai, Fan Changchun, Peng Shanglong, Wang Gang, Hou Juan, Yu Feng, Shi Yulin
Key Laboratory for Green Process of Chemical Engineering of Xinjiang Bingtuan, School of Chemistry and Chemical Engineering, Shihezi University, Shihezi 832003, P. R. China.
National & Local Joint Engineering Laboratory for Optical Conversion Materials and Technology, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, P.R. China.
Dalton Trans. 2020 May 26;49(20):6587-6595. doi: 10.1039/d0dt00925c.
Designing low-cost and high-performance bifunctional electrocatalysts towards hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is vitally important for water splitting. Herein, we synthesize Co2-xNixO2 (0 < x < 1.0) hexagonal nanosheets with different Co/Ni molar ratios via a facile coprecipitation process followed by calcination under an Ar atmosphere. Changing the Co/Ni molar ratios of the Co2-xNixO2 products is found to have a momentous influence on the microstructures, specific surface areas and electrocatalytic performances. At a Co/Ni molar ratio of 0.6, the Co1.4Ni0.6O2 nanosheet exhibits the largest specific surface area of 60.63 m2 g-1, the best OER with an onset overpotential of 278.5 mV, and HER of 72.8 mV as a bifunctional electrocatalyst. Meanwhile, the minimum Tafel slope is 113.6 mV dec-1 for OER and 77.4 mV dec-1 for HER. The Co1.4Ni0.6O2 nanosheet has excellent OER and HER activity at 0.1 mg cm-2 trace loading. Moreover, we construct an overall water splitting cell using the Co1.4Ni0.6O2 bifunctional electrocatalyst in a two-electrode system to further demonstrate the practical application, which needs a cell voltage of 1.75 V at a current density of 10 mA cm-2 and exhibits great long-term stability. These results provide an efficient strategy for the rational design of Co-based oxides towards bifunctional overall water electrocatalysts.
设计用于析氢反应（HER）和析氧反应（OER）的低成本、高性能双功能电催化剂对于水分解至关重要。在此，我们通过简便的共沉淀法合成了具有不同Co/Ni摩尔比的Co2-xNixO2（0 < x < 1.0）六角形纳米片，随后在氩气气氛下进行煅烧。发现改变Co2-xNixO2产物的Co/Ni摩尔比对微观结构、比表面积和电催化性能有重大影响。在Co/Ni摩尔比为0.6时，Co1.4Ni0.6O2纳米片表现出最大比表面积60.63 m2 g-1，作为双功能电催化剂，其析氧反应的起始过电位为278.5 mV，析氢反应为72.8 mV。同时，析氧反应的最小塔菲尔斜率为113.6 mV dec-1，析氢反应为77.4 mV dec-1。Co1.4Ni0.6O2纳米片在0.1 mg cm-2的微量负载下具有优异的析氧反应和析氢反应活性。此外，我们在两电极系统中使用Co1.4Ni0.6O2双功能电催化剂构建了一个全水解电池，以进一步证明其实际应用，在10 mA cm-2的电流密度下，该电池需要1.75 V的电池电压，并表现出良好的长期稳定性。这些结果为合理设计用于双功能全水电催化剂的钴基氧化物提供了一种有效策略。
