“…Photosensitive metal-oxide semiconductors with different energy band gaps (Eg) have been studied for many applications, including solar cells [ 1 , 2 ], photodetectors [ 3 , 4 ], photocatalysts [ 5 , 6 ], water splitting [ 7 , 8 ] and photoelectrochemistry (PEC) [ 9 , 10 ]. In general, extra carriers can be generated based on the absorption of photons with an energy higher than the band gap of a semiconductor (e.g., hν ≥ Eg) [ 11 ].…”