Regulating Water‐Reduction Kinetics in Cobalt Phosphide for Enhancing HER Catalytic Activity in Alkaline Solution

• Published in: Advanced materials (Weinheim) 2017-07, Vol.29 (28), p.n/a
• Main Authors: Xu, Kun, Ding, Hui, Zhang, Mengxing, Chen, Min, Hao, Zikai, Zhang, Lidong, Wu, Changzheng, Xie, Yi
• Format: Article
• Language: English
• Subjects: Adsorption; Catalysis; Catalytic activity; Cost engineering; Electrocatalysts; Energy consumption; Energy of dissociation; Energy storage; Free energy; Hydrogen; hydrogen adsorption free energy; Hydrogen evolution reactions; Hydrogen storage; Hydrogen-based energy; hydrogen‐evolution reaction; Optimization; Oxygen; oxygen incorporation; Reaction kinetics; Renewable energy; Synergistic effect; water dissociation; Water splitting
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.201606980

Electrochemical water splitting to produce hydrogen renders a promising pathway for renewable energy storage. Considering limited electrocatalysts have good oxygen‐evolution reaction (OER) catalytic activity in acid solution while numerous economical materials show excellent OER catalytic performance in alkaline solution, developing new strategies that enhance the alkaline hydrogen‐evolution reaction (HER) catalytic activity of cost‐effective catalysts is highly desirable for achieving highly efficient overall water splitting. Herein, it is demonstrated that synergistic regulation of water dissociation and optimization of hydrogen adsorption free energy on electrocatalysts can significantly promote alkaline HER catalysis. Using oxygen‐incorporated Co2P as an example, the synergistic effect brings about 15‐fold enhancement of alkaline HER activity. Theory calculations confirm that the water dissociation free energy of Co2P decreases significantly after oxygen incorporation, and the hydrogen adsorption free energy can also be optimized simultaneously. The finding suggests the powerful effectiveness of synergetic regulation of water dissociation and optimization of hydrogen adsorption free energy on electrocatalysts for alkaline HER catalysis. Developing highly efficient electrocatalysts in an alkaline electrolyte for the hydrogen‐evolution reaction (HER) is significant for realizing efficient overall water splitting. The coordinative effect of engineering a water dissociation step and the hydrogen adsorption free energy in Co2P by oxygen incorporation can lead to 15 times enhancement of the HER catalytic activity in alkaline solution. A new strategy for the design of advanced alkaline HER electrocatalysts is thus provided.