Photoelectrochemical Hydrogen Generation And Environmental Application Based On Semiconductor Silicon

As a significant method to solve the problem of energy and environment problem with solar energy,photoelectrochemistry(PEC)has attracted public attentions all around the world due to its high efficiencies,environmental friendliness and so on.As an important member in semiconductor industries especially photovoltage(PV)industry,semiconductor silicon has shown its potential in the PEC cells,and would promote the emerging of PEC method.To promote the PEC performance of Si electrodes,the modification of Si surface and the addition of cocatalysts are common used.In the modification of surface,wire-like or pore-like structures have been obtained by chemical etching.As to the usage of catalysts,Pt still plays the hero.However,the single role of modification has its limitations in the promotion of PEC performance.What’s more,the low abundance and high price of Pt restrict its application in PECs.Based on researches currently,this thesis mainly focuses on the preparation of high PEC performance Si electrodes with metal-assisted chemical etching and designing low-cost and high abundant co-catalysts for PEC hydrogen generation.In addition,the role of b-Si for PEC reduction of nitrates has been discussed at last.The main results are concluded as follows:(1)Nanoporous black silicon electrodes have been prepared by metalassisted chemical etching method with chemical pre-deposited of Ag.Combining the surface morphology and PEC results of b-Si electrodes,the best control conditions for preparation of b-Si have been found,namely 30-40 s deposited of Ag and 6 min of oxidized time.(2)The co-catalysts [Mo3S13]2-for replacing of Pt have been synthesis and purified.The simple dropcoating of co-catalysts on b-Si have constructed [Mo3S13]2-/b-Si structure.And this structure shows high PEC hydrogen generation performance.(3)The bare nanoporous black silicon electrodes with best PEC performance have been used to reduce nitrates.This experiment confirms the reduction of nitrate to nitrite and the best conditions of pH 1 and 2 for nitrate reduction process.