Lattice Oxygen-Mediated CO<sub>2</sub> Photothermal Reduction with Tunable CO/H<sub>2</sub> Ratio on K-Doped Nb<sub>2</sub>O<sub>5</sub> Nanoribbons
Xuanyu Yue, Zhijie Wang, Wei Ni, Ke Wang, Yanran Cui, Zhenglong Li
Abstract
Thermocatalytic or photocatalytic CO 2 reduction to CO─without H 2 or sacrificial hole scavengers─remains challenging due to prohibitively high energy barriers or the lack of coupled oxidation half-reactions. Photothermal catalysis enables autonomous CO 2 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 Nb 2 O 5 nanoribbons (K–Nb 2 O 5 NRs) that synergistically integrate photothermal energy and lattice oxygen redox cycling to effect direct CO 2 decomposition under mild photothermal conditions (50–250 °C). The K–Nb 2 O 5 NRs achieve CO production rates of 4.1–405 μmol·g –1 ·h –1 with 100% selectivity, outperforming undoped Nb 2 O 5 by 6.3-fold at 250 °C. Mechanistic studies reveal that K doping optimizes the electronic structure of Nb 2 O 5, accelerating oxygen vacancy regeneration and enhancing CO 2 adsorption. At the same time, the photothermal effect decouples lattice oxygen oxidation (photogenerated holes) and CO 2 reduction (photogenerated electrons), thereby suppressing electron–hole recombination. By introducing H 2 O as a dynamic oxygen chemical potential modulator, the H 2 /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 CO 2 conversion.