Concentrated solar CO₂ reduction in H₂O vapour with >1% energy conversion efficiency

H₂O dissociation plays a crucial role in solar-driven catalytic CO₂ methanation, demanding high temperature even for solar-to-chemical conversion efficiencies <1% with modest product selectivity. Herein, we report an oxygen-vacancy (V₀) rich CeO₂ catalyst with single-atom Ni anchored around its surface V₀ sites by replacing Ce atoms to promote H₂O dissociation and achieve effective photothermal CO₂ reduction under concentrated light irradiation. The high photon flux reduces the apparent activation energy for CH₄ production and prevents V₀ from depletion. The defects coordinated with single-atom Ni significantly promote the capture of charges and local phonons at the Ni d-impurity orbitals, thereby inducing more effective H₂O activation. The catalyst presents a CH₄ yield of 192.75 µmol/cm²/h, with a solar-to-chemical efficiency of 1.14% and a selectivity ~100%. The mechanistic insights uncovered in this study should help further the development of H₂O-activating catalysts for CO₂ reduction and thereby expedite the practical utilization of solar-to-chemical technologies. Efficiency in this system reaches 1.14%. In-depth mechanism investigations using experimental and theoretical methods demonstrate that V₀ regenerated on the catalyst surface ensures a steady supply of active sites for CO₂ reduction. DFT and TDDFT calculations confirm the crucial roles of Ni and V₀ in enhancing carrier kinetics and reactant activation, and AIMD/TDDFT demonstrate H₂O dissociation proceeds via thermally assisted photocatalysis under concentrated irradiation.

Yuqi Ren, Yiwei Fu, Naixu Li, Changjun You, Jie Huang, Kai Huang, Zhenkun Sun, Jiancheng Zhou, Yitao Si, Yuanhao Zhu, Wenshuai Chen, Lunbo Duan, Maochang Liu