A two-electron migration mechanism co-constructed by K+ passivation and defect engineering for efficient TiO2 photocatalytic hydrogen evolution

Abstract

As a promising candidate for photocatalytic hydrogen evolution reaction, Pt/TiO2 photocatalysts with low cost and high activity are considered to be one of the most ingenious strategies for obtaining both high-purity hydrogen and high-value products using inexhaustible sunlight as the sole driving force. In this work, a TiO2 microsphere with internal defect engineering co-constructed by oxygen vacancies (Ov) and B-doping was prepared by using a one-step solvent volatilization method, whose surface was cleverly modified by the K+ passivation layer. Compared with the hydrogen evolution activity of pure TiO2 (2.7 μmol/g/h), that of HB-TiO2 was improved by 460% (124 μmol/g/h), while that of KHB-TiO2 was improved by 1300% (352 μmol/g/h). The prominent performance is attributed to the accelerated carrier separation induced by the internal defect-engineering and the efficient two-electron migration mechanism assisted by the K+ passivation layer. On the premise of not destroying the internal defect engineering that facilitates carrier separation, the fascinating surface K+ passivation mechanism inhibits carrier recombination and improves visible light utilization by healing the electronic structure of the TiO2 surface and then using Pt-Ti metal bonds to directly migrate two-electron to Pt for the hydrogen evolution reaction. Our work demonstrates the promising strategy for the modification of defective TiO2 microspheres with K+ passivation layer, opening a new avenue for the construction of a two-electron migration mechanism for efficient hydrogen evolution reaction.