Caged-Cation-Induced Lattice Distortion in Bronze TiO₂for Cohering Nanoparticulate Hydrogen Evolution Electrocatalysts

Defect engineering provides a promising approach for optimizing the trade-off between support structures and active nanoparticles in heterojunction nanostructures, manifesting efficient synergy in advanced catalysis. Herein, a high density of distorted lattices and defects are successfully formed in bronze TiO₂through caging alkali-metal Na cations in open voids (Na-TiO₂(B)), which could efficiently cohere nanoparticulate electrocatalysts toward alkaline hydrogen evolution reaction (HER). The RuMo bimetallic nanoparticles could directionally anchor on Na-TiO₂(B) with a certain angle of ∼22° due to elimination of the lattice mismatch, thus promoting uniform dispersion and small sizing of supported nanoparticles. Moreover, caging Na ions could significantly enhance the hydrophilicity of the substrate in RuMo/Na-TiO₂(B), leading to the strengthening synergy of water dissociation and hydrogen desorption. As expected, this Na-caged nanocomposite catalyst rich with structural perturbations manifests a 6.4-fold turnover frequency (TOF) increase compared to Pt/C. The study provides a paradigm for designing stable nano-heterojunction catalysts with lattice-distorted substrates by caging cations toward advanced electrocatalytic transformations.