Nearly 100% selectivity of photothermal CO₂ reduction into CH₄ achieved by Pt/Sr₂Nb₂O₇ heterojunction

Developing efficient and highly selective photocatalytic CO₂ reduction catalysts remains one of the most significant challenges in achieving carbon neutrality. Herein, the efficient conversion of CO₂ to CH₄ with selectivity close to 100% was achieved by loading uniformly dispersed Pt nanoparticles on the surface of Sr₂Nb₂O₇ nanosheets; the optimal CH₄ yield was as high as 15.65 μmol/g/h. Various characterizations demonstrate that Pt nanoparticles have a significant photothermal effect that can increase the catalyst surface temperature, and improve the performance and electron transport rate of the catalyst. Additionally, Pt nanoparticles and Sr₂Nb₂O₇ nanosheets form heterojunctions, which facilitate the separation of photogenerated carriers and aggregation of photogenerated electrons on the Pt nanoparticles. Pt nanoparticles become new reactive sites that have a strong adsorption impact on the key intermediate ∗CO and reduce the reaction energy barrier of ∗CHO generation. The results revealed that the synergy between electron accumulation, strong adsorption of ∗CO, and reduction of the reaction potential of ∗CHO are the reasons for the efficient and selective conversion of CO₂ to CH₄. This work provides novel insights into the role of metal-based cocatalysts in selective CO₂ photoconversion and new ideas for designing efficient CO₂ conversion systems.