Defect-phase engineered NiTi-TiO2 enabling near-unity selective photocatalytic CO2-to-methanol conversion

Scaling up methanol yields by artificial photosynthesis at a modest cost remains thermodynamically challenge. Designing concerted reaction sites to control intermediate evolution and stimulate proton-coupled electron transfer (PCET) is necessary. Here we show a nickel-titanium-based catalyst that achieves near-millimolar hourly methanol yields with 99.79% selectivity and a solar-to-chemical conversion efficiency of 2.23%. This catalyst is synthesized through one-step etching of NiTi-layered double hydroxide, which generates abundant unsaturated sites, along with the in-situ formation of amorphous TiO2. Revealed by in-situ characterizations, these defect-rich units effectively suppress the formation of undesirable carbonate while promoting the favorable *COOH intermediate. Furthermore, theoretical simulations confirm this *COOH boost facilitates the production of *CO and accelerates the PCET steps. This work significantly advances efficient methanol production by artificial photosynthesis and offers fundamental insights into controlling reaction pathways for renewable fuel synthesis. Artificial photosynthesis to produce CH3OH holds promise but faces selectivity challenges. Here, the authors report a defect-phase synergetic NiTi-TiO2 system that achieves almost 100% CH3OH selectivity in pure H2O by successfully controlling the evolution of key reaction intermediates.