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 (V_o) rich CeO₂ catalyst with single-atom Ni anchored around its surface V_o 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 V_o 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.