Engineering Heterostructure of S‐Doped MoSe ₂ Quantum Dots and MXene‐Derived TiO ₂ Nanosheets for Highly Efficient Noble Metal‐Free Catalysts for Photocatalytic and pH‐Universal Electrocatalytic Hydrogen Evolution

This work demonstrates the synthesis of S‐doped MoSe 2 (S‐MoSe 2 ) quantum dots (QDs) grown on MXene‐derived 2D rutile TiO 2 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 MoSe 2 , 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‐MoSe 2 /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‐MoSe 2 /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 MoSe 2 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‐MoSe 2 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.