Lattice Oxygen-Mediated CO2 Photothermal Reduction with Tunable CO/H2 Ratio on K-Doped Nb2O5 Nanoribbons

Thermocatalytic or photocatalytic CO2 reduction to CO─without H2 or sacrificial hole scavengers─remains challenging due to prohibitively high energy barriers or the lack of coupled oxidation half-reactions. Photothermal catalysis enables autonomous CO2 dissociation via synergistic photon-thermal activation under mild conditions. However, it remains a grand challenge to design high-performance catalysts that achieve rapid lattice oxygen dynamic equilibrium by harmonizing photogenerated carriers with thermal lattice vibrations. Here, we report K-doped Nb2O5 nanoribbons (K–Nb2O5 NRs) that synergistically integrate photothermal energy and lattice oxygen redox cycling to effect direct CO2 decomposition under mild photothermal conditions (50–250 °C). The K–Nb2O5 NRs achieve CO production rates of 4.1–405 μmol·g–1·h–1 with 100% selectivity, outperforming undoped Nb2O5 by 6.3-fold at 250 °C. Mechanistic studies reveal that K doping optimizes the electronic structure of Nb2O5, accelerating oxygen vacancy regeneration and enhancing CO2 adsorption. At the same time, the photothermal effect decouples lattice oxygen oxidation (photogenerated holes) and CO2 reduction (photogenerated electrons), thereby suppressing electron–hole recombination. By introducing H2O as a dynamic oxygen chemical potential modulator, the H2/CO ratio is continuously tuned from 1.4 to 0.3 through competitive adsorption at oxygen vacancy sites. Remarkably, the catalyst maintains syngas production for 50 h in a flow reactor. This study provides new ideas for the design of catalysts for photothermal CO2 conversion.