Efficient photoreduction of CO2 to complete CO catalyzed by electrospun Cu-doped In2O3 nanofibers

The photocatalytic conversion of anthropogenic carbon dioxide (CO 2 ) into solar fuels using semiconductor nanomaterials represents a promising and sustainable approach to addressing both energy sustainability and climate change concerns. Developing highly efficient semiconductor-based photocatalysts to tailor reaction pathways of CO 2 reduction is the key to producing value-added products with desirable performance. Herein, we report a novel copper-doped indium oxide (Cu-doped In 2 O 3 ) nanostructure prepared via the electrospinning technique, followed by annealing to enhance photocatalytic CO 2 reduction. Our findings demonstrate that modifying the bulk In 2 O 3 with copper enables Cu-doped In 2 O 3 nanofibers to catalyze the CO 2 reduction reaction more efficiently. In situ FTIR spectra measurements were utilized to identify the reaction intermediates and gaseous products for validating the reaction pathway. Combined with in situ electron paramagnetic resonance (EPR) and vibrational spectroscopy measurements, which revealed that interstitial Cu doping induces lattice distortions and oxygen vacancy (O V ) formation, effectively enhancing visible light absorption, accelerating charge separation, and migration. Consequently, the optimized In 2 O 3 -Cu3% nanofiber photocatalyst demonstrated outstanding selectivity (100 %) and a CO production rate of 45.5 μmol·g −1 ·h −1 , which is approximately six times higher than In 2 O 3 . Mechanistic studies have indicated that O V defects serve as electron reservoirs to suppress the recombination of photogenerated charges, while simultaneously creating abundant CO 2 chemisorption sites in nanostructures.