Energy-Efficient Hydrogen Evolution Reactions via Hydrazine Oxidation over Facile Synthesis of Cobalt Tetraoxide Electrodes
Xiaohu Xu, Tao Wang, Lijuan Dong, Wenbo Lu, Xiangyang Miao
Abstract
Clean hydrogen energy is regarded as a promising alternative in terms of energy conversion and storage. Meanwhile, transitional metal oxides (TMOs) have stimulated more and more research attention because of their unique performance, holding broad prospects in expediting the tardy oxygen evolution reaction (OER) in electrolyzing water. However, facile and highly efficient synthesis of TMOs to garner excellent electrocatalytic performance has by far remained difficult. Herein, a three-dimensional (3D) self-supported microstrip-like Co3O4 assembled from a tiny nanocube electrocatalyst, grown in situ on commercial Co foam (denoted as Co3O4/Co), is fabricated through a facile one-step hydrothermal synthesis method, where the sluggish anodic OER is replaced by a more thermodynamically oxidized hydrazine oxidation reaction (HzOR) for assisting energy-saving hydrogen generation in alkaline media. The synthesized electrocatalyst shows appreciable HzOR performances, producing a current density of 200 mA cm–2 at −32 mV and a Tafel slope of 53.43 mV dec–1. Remarkably, an ultrasmall-cell voltage of merely 1 V is required to deliver 764 mA cm–2 in a coupled electrode electrolyzer with excellent stability at room temperature, which is outperforming the precious metal catalyst system and the reported noble-metal-free electrocatalysts. Further, the Faradaic efficiency of the as-fabricated electrocatalyst is close to 100%. Considering the high electrocatalytic efficiency for the HzOR, the Co3O4/Co proves to be a kind of energy-saving electrocatalyst for the HzOR with great potential.