Coupled spinel manganese−cobalt oxide and MXene electrocatalysts towards efficient hydrogen evolution reaction

Abstract

A convenient and cost-effective strategy is developed to the controllable fabrication of the small-sized spinel MnCo 2 O 4 nanocrystals strongly coupled with 2D Ti 3 C 2 T x MXene nanosheets, which express exceptional electrocatalytic ability towards the hydrogen evolution reaction. • Heterojunction catalysts made from spinel MnCo 2 O 4 and MXene are first synthesized. • Ultrafine MnCo 2 O 4 nanocrystals are homogeneously dispersed on the MXene surface. • The intimate 0D/2D interfacial connection enables strong electronic interactions. • The newly-designed catalysts show superior electrocatalytic ability for hydrogen evolution. Although nanostructured spinel oxides have been considered as potential electrode materials for the hydrogen evolution reaction (HER), their catalytic properties still need to be substantially improved to meet the requirements of practical use. In this work, we present the rational design and controllable synthesis of nanosized spinel manganese−cobalt oxide strongly coupled with ultrathin Ti 3 C 2 T x MXene nanosheets (MnCo 2 O 4 /Ti 3 C 2 T x ) through a facile and cost-effective strategy. The effective combination of spinel MnCo 2 O 4 with Ti 3 C 2 T x nanosheets generates a number of attractive structural features with strong synergistic effects, such as highly accessible surface areas, intimate 0D/2D interfacial connection, full exposure of abundant active sites, optimized electronic structure, and excellent electron conductivity, all of which are very desirable for the HER process. Consequently, the resulting MnCo 2 O 4 /Ti 3 C 2 T x electrocatalyst possesses an unusual HER ability with a low onset potential of only 51 mV, a small Tafel slope of 79 mV dec −1 and exceptional long-term stability, markedly outperforming the bare MnCo 2 O 4 and Ti 3 C 2 T x electrocatalysts.