Influnce Of Photo-Generated Electrons Migration On Photocatalytic Water Splitting Of Defective SnO₂/g-C₃N₄

This thesis is focused on the water splitting into hydrogen catalyzed by defective SnO2/g-C3N4 under visible light. Different catalytic performances were obtained via tailoring oxygen vacancy concentrations. The photo-generated electrons migration property was discussed based on the catalytic performances variation and systematic sample characterizations. The main results could be summarized as follows:(1)SnO2 nano-crystals with given amounts of oxygen vacancies were fabricated by two-step method using hydrothermal and annealing methods. Then defective SnO2 nanocrystals were hybridized with g-C3N4 in different mass ratios. As the surface oxygen vacancycontentswere varied with SnO2 mass ratios, hybrids showed double performance maxima. Based on the corresponding characterizations, the relation between photo-generated electron competitive migration and photocatalytic performance were discussed.(2)SnO2 nano-crystals with different grain sizes were fabricated by annealing SnO2 quantum dots at different temperatures. With the utilization of the thermal insulation filter, the synergy among oxygen vacancy, grain size and infrared light on hybrids photocatalytic hydrogen generation performance from water splitting under visible light was investigated. When SnO2 grain size is smaller twice that of its Debye length, the secondary excitation of bounded electrons were stimulated by phonon under infrared light irradiation. This secondary excitation retains a higher catalytic performance of SnO2/g-C3N4.The results reported in this thesis are very important, which may help to get insight into the photo-generated electron migration and photo-catalytic hydrogen production for semiconductor/g-C3N4hybrids.