High-Performance Ni<sub><i>x</i></sub>Co<sub>3-x</sub>O<sub>4</sub>/Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub>-HT Interfacial Nanohybrid for Electrochemical Overall Water Splitting
Peiwen Xu, Hehui Wang, Jun Liu, Xinzhen Feng, Weijie Ji, Chak‐Tong Au
Abstract
This study highlights the facet structure control of regular NixCo3–xO4 nanoplates and interfacial modulation through elemental doping and morphologically fitted assembly of Ti3C2Tx nanosheets for high performances in OER/HER and overall water splitting. Over the resulting Ni0.09Co2.91O4/Ti3C2Tx-HT in a solution of 1 M KOH, the OER and HER overpotentials of 262 and 210 mV, respectively, are achievable at a current density of 10 mA cm–2. In the case of the overall water splitting by using Ni0.09Co2.91O4/Ti3C2Tx-HT as anode and cathode catalysts, only a potential of 1.66 V is needed to obtain a current density of 10 mA cm–2, and the catalysts can stand for a period of 70 h, remarkably outperforming the RuO2–Pt/C-based catalyst and benefiting from the intensive association and interfacial function between the Ti3C2Tx and NixCo3–xO4 nanosheets. Interestingly, a surface reconstruction from the (112) to (111) facet structure occurred upon the fine-tuned Ni doping of regular NixCo3–xO4 hexagonal nanoplates and led to a highly active catalyst surface. At x = 0.09, the amount of Ni3+ becomes the highest, which is favorable for the generation of the critical OH intermediates on NixCo3–xO4/Ti3C2Tx-HT. The current study documented the significance of the well-controlled interfacial assembly of transition-metal oxide/MXenes as an effective electrocatalyst in the OER/HER and overall water splitting processes and provided the insights into the structure–performance correlation over such kinds of precious metal-free catalysts.