Boosting Solar Methanol Production over Hierarchical Carbon Nanocage-Supported In₂O_3–x via Photoenhanced Electron Buffering Effect

Solar methanol production represents a key technology meaningful for the production of liquid fuels as well as carbon neutralization. However, it is faced with the crucial challenge of limited reaction rate, selectivity, and stability. In this study, we develop a hierarchical carbon nanocage (hCNC)-supported In 2 O 3 synergistic catalyst for robust methanol production driven solely by sunlight. hCNC plays a unique role as “electron buffers” for dynamic modulation of the oxygen vacancy (O v ) concentration in In 2 O 3, addressing the long-standing challenge of O v -induced destabilization. Notably, the photoenhanced electron buffering enables both electron transfer toward O v -deficient In 2 O 3, promoting O v generation, and electron extraction from O v -rich In 2 O 3– x, preventing over-reduction. Consequently, both the high- and low-energy photons in the solar spectrum were harvested toward synergistic photothermal/photochemical catalysis, achieving a record-high methanol production rate of 4.6 mmol·g cat –1 ·h –1 with >51% selectivity. Our discovery of the photoenhanced electron buffering provides a perspective for dynamic modulation of nonthermal photocatalytic mechanisms; besides, the synergistic combination of photochemical and photothermal pathways also provides important guidelines for efficient solar methanol production.