Surface excited MoO2 to master full water splitting

• Published in: Electrochimica acta 2020-11, Vol.359, p.136929, Article 136929
• Main Authors: Wang, Bobo, Zhang, Zhe, Zhang, Shanshan, Cao, Yuncheng, Su, Yong, Liu, Shude, Tang, Wei, Yu, Junxi, Ou, Yun, Xie, Shuhong, Li, Jiangyu, Ma, Ming
• Format: Article
• Language: English
• Subjects: Electrocatalysts; Electrodes; HER; Hydrogen; Hydrogen evolution reactions; Hydrogen production; Hydrogen-based energy; Metal foams; Molybdenum oxides; MoO2; OER; Oxidation; Oxygen evolution reactions; Oxygen vacancy; Substrates; Vacancies; Water splitting
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2020.136929

•MoO2 nanosheets were fabricated on nickel foam through hydrothermal method.•Post-modification by Hydrazine solution could introduce oxygen vacancies to the surface of MoO2 nanosheets.•Oxygen vacancies enhanced conductivity and improved surface reaction kinetics of MoO2.•The post-treatment process for oxygen vacancies provides an effective strategy for improving electrocatalysis. Electrocatalytic water splitting, including hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), is an ideal method to produce hydrogen energy source. Stable electrocatalysts with good electrolytic activity are crucial for long-term water splitting. In this work, we show that MoO2 nanosheets can be grown directly on nickel foam substrate with oxygen vacancies decorated on the surface, acting as an excellent electrocatalyst for practical water splitting. In comparison to the pristine sample, the optimized MoO2, treated by 2% N2H4 solution for 20 min, exhibits a relatively low onset potential of −60 mV vs. reversible hydrogen electrode (RHE) for HER and a cell voltage of about 1.6 V vs. RHE to achieve a current density of 85 mA cm−2 for OER, which are attributed to the enhanced conductivity and improved surface active sites facilitated by oxygen vacancies. With the accelerated hydrogen generation process and activated water oxidation reaction, MoO2 is demonstrated to be a suitable and stable bifunctional electrode for full water splitting, and the post-treatment process for oxygen vacancies also provides an effective strategy for improving electrocatalysis. [Display omitted]