Photo-assisted Electrocatalytic Oxidation Of Small Organic Alcohols And Photocatalytic Hydrogen Production

Fuel cells directly convert chemical energy in fuels into electrical energy,which is regarded as the first choice for clean energy technology in the 21st century.However,the commercialization of fuel cells still faces many challenges,such as the hydrogen source of H2-O2 fuel cells and the slow reaction kinetics of alcohol electro-oxidation for alcohol fuel cells.To solve these problems,this thesis intends to employ solar energy to promote the efficiency.For hydrogen production from photocatalytic water splitting,a strategy combining energy band regulation with interface engineering is proposed to promote the separation of photo-generated electron-hole pair.For direct alcohol fuel cells,focusing on the slow kinetics of alcohol electro-oxidation?AOR?,a synergetic effect between photocatalysis and electrocatalysis was put forward to promote the AOR.With the help of spectroscopy,microscopy,electrochemical techniques,combining density functional theory calculation?DFT?,the relationship of microstructure-performance of the catalysts and its catalytic behavior are thoroughly studied.The main research contents are as follows:?1?The CoP quantum dots?CoPQD/P-g-C3N4?highly dispersed on the interstitial P-doped g-C₃N₄ was prepared by a one-step phosphating process,Which displays excellent photocatalytic activity for both hydrogen production from water electrolysis and pollutant degradation as a bifunctional catalyst.With CoPQD/P-g-C3N4 as a photocatalyst,the maximum hydrogen production rate of water decomposition reached 724?mol g^-11 h^-1.Compared with the Pt-based catalyst?321?mol g-1 h-1?,the hydrogen production rate was almost double.A good stability of CoPQD/P-g-C₃N₄ was also demonstrated in a continuous 15h life test.CoPQD/P-g-C₃N₄ can complete the degradation of rhodamine B?20 min?and methyl orange?50 min?in a short time.Studies on the structure-activity relationship of the CoPQD/P-g-C₃N₄ composite photocatalyst show that the main reason for its high photocatalytic performance is due to the energy band matching of the heterojunction and the tight interface formed by the Co-P interface bond which promoted the photogenerated charge separation and transfer.?2?A semiconductor nanocubic WO₃ supported PtRu alloy catalyst was prepared by an ethylene glycol reduction method.The prepared PtRu-WO₃ showed good photocatalytic activity for the electro-oxidation of alcohol?AOR?,such as methanol,ethanol and ethylene glycol.The introduction of light significantly reduced the initial oxidation potential of the above-mentioned alcohol,and the AOR current was also significantly improved.Compared with the case wihout light,the initial oxidation potential of AOR is shifted negatively by about 100 mV,and the peak current density is increased by 3?5 times.When this catalyst was used as the anode catalyst for a light-assisted direct alcohol fuel cell,its maximum power density was 11.1 mW mg_Pt^-1,which was 23.8 times of that without light(0.47 mW mg_Pt^-1).The kinetic studies indicated that the introduction of light decreased the activation energy of AOR,reduced the charge transfer resistance,and expedited the oxidative removal of strongly adsorbed species during the reaction,thereby promoting the electrocatalytic oxidation of alcohol molecules.