High-Performance NixCo3-xO4/Ti3C2Tx-HT Interfacial Nanohybrid for Electrochemical Overall Water Splitting.

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.