[127] Engineering heterostructure of S-doped MoSe₂ quantum dots and MXene-derived TiO₂ nanosheets for highly efficient noble metal-free catalysts for photocatalytic and pH-universal electrocatalytic hydrogen evolution

This work demonstrates the synthesis of S-doped MoSe₂ (S-MoSe₂) quantum dots (QDs) grown on MXene-derived 2D rutile TiO₂ nanosheets (MTS) for highly efficient and durable noble metal-free catalyst for both photocatalytic and electrocatalytic hydrogen evolution reaction (HER) under universal pH conditions. The incorporation of sulfur atoms effectively modulates the electronic structure of MoSe₂, enhancing active site density and improving charge transfer efficiency, while 2D MTS provides a high surface area support and strong interfacial interaction. The synthesized S-MoSe₂/MTS catalyst demonstrates the superior visible-light absorption, leading to highly efficient photocatalytic hydrogen production yield of 1054 µmol·h⁻¹·g⁻¹ with excellent durability. Furthermore, the S-MoSe₂/MTS catalyst performs the outstanding electrochemical activity of HER with low overpotentials and long-term stability under pH-universal conditions. The density functional theory (DFT) study shows that the sulfur doping in MoSe₂ decreases the energy barrier for water dissociation and tunes the Gibbs free energy of hydrogen intermediates to values favorable for catalytic reactions. In addition, the built-in electric field between S-MoSe₂ and MTS promotes charge separation and improves electrical conductivity. This synergistic effect leads to excellent photocatalytic and electrocatalytic hydrogen generation. This study provides a promising strategy for noble metal-free catalysts with excellent photocatalytic and electrocatalytic performance for hydrogen production.