In situ topotactic transition to porous crystals boosts methane photooxidation

The rapid recombination of photogenerated electron-hole pairs represents a fundamental bottleneck in photocatalysis. Constructing porous single crystals is expected to resolve this issue by simultaneous optimization of light absorption, charge transport and mass diffusion. Here, we present a topotactic lattice contraction strategy for synthesizing porous single-crystalline zinc blende ZnO monoliths with exceptional crystallinity, phase purity and high porosity. In situ transmission electron microscopy reveals the atomic-scale formation process: preferential S/O migration along {222} channels enable epitaxial nucleation, while interfacial strain induces vacancy coalescence into interconnected nanopores. The low defect density in ZnO effectively suppresses photogenerated carrier recombination, exhibiting improved charge transport and prolonged carrier lifetime. Incorporating atomically dispersed Ru sites (0.6 wt%) further enhances charge separation efficiency, achieving 82% selectivity for methyl hydroperoxide in methane photooxidation while maintaining >85% activity over 40 hours. This work establishes a route to porous single crystals, advancing material design for prospective application in photocatalysis.