Anchoring isolated Pd atoms on Ti3C2Tx MXene with boosted kinetics for alkaline hydrogen evolution

Developing efficient catalysts with accelerated kinetics towards alkaline hydrogen evolution reaction (HER) is of vital importance but still challenging owing to the sluggish processes, including water adsorption, water dissociation, and hydrogen adsorption. Herein, we presented a facile strategy to anchor isolated Pd atoms on Ti3C2Tx MXene (Pd1-Ti3C2Tx) to simultaneously regulate the adsorption of intermediates for accelerated HER kinetics under alkaline conditions. Mechanism studies suggested that Pd1-Ti3C2Tx could effectively strengthen the H2O adsorption and dissociation owing to the strong electron interaction between O 2p orbital in H2O and Pd 3d orbital in Pd1-Ti3C2Tx. Meanwhile, the hydrogen adsorption on Ti3C2Tx MXene could be further optimized due to the downshifted p-band center of surface O sites caused by the anchoring of Pd atoms. Accordingly, Pd1-Ti3C2Tx showed a much lower overpotential and smaller Tafel slope in comparison with that of pure Ti3C2Tx. This work provides a fundamental understanding of designing electrocatalysts with regulated kinetics through the single-atom-modulation strategy.