Single platinum atoms immobilized on an MXene as an efficient catalyst for the hydrogen evolution reaction

摘要

Single-atom catalysts offer a pathway to cost-efficient catalysis using the minimal amount of precious metals.However,preparing and keeping them stable during operation remains a challenge.Here we report the synthesis of double transition metal MXene nanosheets-Mo2TiC2Tx,with abundant exposed basal planes and Mo vacancies in the outer layers-by electrochemical exfoliation,enabled by the interaction between protons and the surface functional groups of Mo2TiC2Tx.The as-formed Mo vacancies are used to immobilize single Pt atoms,enhancing the MXene’s catalytic activity for the hydrogen evolution reaction.The developed catalyst exhibits a high catalytic ability with low overpotentials of 30 and 77 mV to achieve 10 and 100 mA cm?2 and a mass activity about 40 times greater than the commercial platinum-on-carbon catalyst.The strong covalent interactions between positively charged Pt single atoms and the MXene contribute to the exceptional catalytic performance and stability.