Study On The Effect And Mechanism Of Metal Oxides On The Photocatalytic Overall Water Splitting Performance Of Red Phosphorous

Overall photocatalytic water splitting to simultaneously generate H₂and O₂plays an important role in solving energy problems.Although a number of semiconductors,in terms of energy band structure requirements,have been reported to be efficient photocatalysts for overall water splitting.The comprehensive performance for photocatalysis is still limited due to the issues including sole absorption of ultraviolet light,serious photocorrosion,low surface area,and rapid carrier recombination.Thus,the key is to exploit novel photocatalysts with high activity for overall water splitting under visible light irradiation.Elemental semiconductors red phosphorus（RP）shows obvious advantages that include economic efficiency,less toxicity,chemical stability,and easy availability when compared with other traditional semiconductors and other types of phosphorus.According to the previous reports,RP is also a novel kind of pure phase photocatalyst with the ability of overall water splitting.However,the overall water splitting activity of RP is low due to the rapid recombination of photocarriers.Based on the above analysis,we developed novel photocatalysts to enhance the activity of RP.The research contents of this work are as follows:（1）Preparation and photocatalytic activity of novel WO₃/RP composite by low-temperature roasting method.2.5%WO₃/RP composite achieved the highest activity for H₂and O₂evolution in pure water without sacrificial agent,which is 7.0 times to that of RP under visible light（λ≥420 nm）.Greatly enhanced photocarriers separation of WO₃/RP was observed by transient photocurrent,electrochemical impendence,photoluminescence and time-resolved photoluminescence characterizations.WO₃/RP composite applied a direct S-scheme mechanism to efficiently separate the photocarriers,which can be obtained from the detection results of active oxygen species.This work provides a guideline for the design of RP-based composite with high activity to realize overall water splitting via a S-scheme mode for photocarriers separation.（2）α-Fe₂O₃modified RP and its enhancement effect on photocatalytic for overall water splitting.Based on the previous research on the enhancement of the performance of the RP-based photocatalyst for overall water splitting,theα-Fe₂O₃/RP composite was prepared by a low temperature hydrothermal method.In the experimental,the 1.5%α-Fe₂O₃/RP composite showed the best overall water splitting performance,which was 6.9times that of RP.Through various characterization studies,the separation efficiency of photogenerated carriers can be found to be significantly improved.It can be attributed to the matching of the energy band positions of the two photocatalysts and the interface contact,that efficiently separate the photocarriers and realizes the synergistic enhancement of photocatalytic performance.This work provides enlightenment for the design of direct S-scheme photocarrier separation mode under visible light to enhance the photocatalytic performance of RP-based composites.