Fabrication Of H-In₂O₃-based Nano-composite Materials And Their Photoelectrochemical Performance

Photoelectrochemical（PEC）water splitting for hydrogen production system is one of the effective ways to solve energy and environmental crisis problems by using solar energy as a source of energy consumption.The performance of the photoanode material plays a decisive role in photoelectrochemical water splitting system.And the main factors that affect the performance of the electrode material are the generation,separation and transport of photogenerated carriers.Transition-metal oxides nanostructures usually considered as photoanode material of photoelectrochemical cell.Among these Transition-metal oxides semiconductors,In₂O₃ has been investigated for many years because of its good electrical conductivity,chemical stability and suitable positioned conduction and valence bands for water splitting.However,research on In₂O₃ as a photoanode is less noticed due to the limitations presented by its wide band gap（3.5 eV）.The absorption and utilization of visible light is inefficient because of the large band gap of In₂O₃,so the overall power conversion efficiency is too low while applied in a PEC cell.In view of this,the specific design and modification of In₂O₃ material are as follows:1.Hydrogen treatment of transition-metal oxides nanostructures is an effective way to improve the material photoelectrochemical properties of the material itself.It is also conducive to the subsequent modification of our research.Under the appropriate hydrogen treatment conditions,we prepared H-In₂O₃ nanocubes and the photoelectrochemical performance is improved.Hydrogen treatment that can address this issue for introducing a moderate amount of oxygen vacancies.These oxygen vacancies could lower the CBM or induce the formation of new energy levels in the band gap,and thus,the band gap is narrowed.The narrowed band gap can increase the photo-generated charge carriers and electrical conductivity of semiconductor metal oxides under white light illumination,thereby improving the efficiency of PEC conversion.Moreover,the donor densities also could be enhanced by introducing the oxygen vacancies after hydrogenation.2.To achieve better PEC performance,noble metal nanoparticles have been extensively adopted in photoanode materials due to its localized surface plasma resonance（LSPR）effect.For the first time,we propose a combination of hydrogen treatment and noble metal nanoparticles deposition modification to prepare HIn₂O₃/Ag heterojunction photoanode material.And we study on the photoelectrochemical properties affected by electrodeposition time of Ag nanoparticles.Ag nanoparticles could act as photosensitizers to strengthen the optical absorption in visible light and enhance the absorption intensity through LSPR effect.Meanwhile,the junctions formed between the semiconductor and noble metal nanoparticles can facilitate the separation of photogenerated charge carriers.The experimental results show that the performance of the material is been improved.3.The construction of type-II heterojunction between In₂O₃ and suitable narrow band gap semiconductors has been demonstrated as a potential solution to improve visible absorption and utilization.The main characteristic of the type II heterojunction is that the band type-II staggered band alignment involve two（wide and narrow）band gap semiconductors,enabling not only the broad absorption of visible light but also the inhibition of charge recombination process.Based on HIn₂O₃/Ag photoanode,for the first time,we creatively combine hydrogen treatment,precious metal deposition,and type II heterojunction to prepare threecomponent H-In₂O₃/Ag/In2S3 nanocubes by an effective electrodeposition method to enhance the PEC properties.Indeed,the experimental results show that the performance of the material is been improved.