Constructing\nHeterojunction Photocatalyst Systems\nwith Spatial Distribution of Au Single Atoms for CO<sub>2</sub> Reduction

In\nsingle-atomic photocatalyst systems, the spatial distribution\nof single atoms on heterojunctions and its impact on photocatalytic\nprocesses, particularly on carrier dynamics and the CO<sub>2</sub> reduction process involving multielectron reactions, remains underexplored.\nTo address this gap, a WO<sub>3</sub>/TiO<sub>2</sub> nanotube heterojunction\nwith a spatially selective distribution of Au single atoms was developed\nusing an oxygen vacancy anchoring strategy for CO<sub>2</sub> photoreduction.\nBy anchoring Au atoms onto the WO<sub>3</sub> or TiO<sub>2</sub> components,\na substantial number of active sites are generated and the electron\ntransfer pathways from the heterojunction toward Au sites are formed,\nthereby enhancing carrier separation and concentration. As a result,\nthe total yield of CO<sub>2</sub> reduction products increases by\n6.3 times and 3.9 times, respectively. More importantly, due to significant\ndifferences in adsorption properties, energy band structures, and\nreaction energy barrier, as well as a 2-fold difference in carrier\nlifetime, the selective distribution of Au single-atom sites results\nin completely different CO<sub>2</sub> photoreduction products: when\nAu atoms are anchored on WO<sub>3</sub> and TiO<sub>2</sub> components,\nthe product selectivity is 67.6% CH<sub>4</sub> and 82.9% CO, respectively.\nThis study clarifies the vital role of the spatial distribution of\nsingle atoms on the selectivity of electron-demanding products.