Regulation Strategies Of Interfacial Electron Migration And Hydrogen Production Of Metallic Sulfide And Bimetallic Oxide

The technology of using inexhaustible solar energy as external energy to promote photocatalyst water splitting has broad application prospects in the future energy field.Its core purpose is to develop high-quality,green,stable and efficient photocatalysts.However,photocatalysts generally have the problem of high recombination rate of photogenerated carriers,resulting in low photocatalytic activity.Therefore,based on the high recombination rate of the photogenerated carriers of the catalyst,this paper adopts a modification strategy to the photocatalyst to enhance the separation ability and migration rate of the photogenerated carriers,thereby improving the photocatalytic activity of the photocatalyst.At the same time,the photogenerated electron transition and migration of photocatalysts have been deeply studied,and the possible mechanism of photocatalytic hydrogen evolution has been proposed,which provides a new strategy for the modification of catalysts.The main research contents are as follows:1.Mo-S is accurately anchored on the surface of CeO₂using a classical heat treatment strategy.The successful recombination of CeO₂and Mo-S leads to the formation of stable Mo-O bonds and S-scheme heterojunction between the catalysts.The high-efficiency photocatalytic hydrogen evolution activity of the composite catalyst is mainly attributed to the following three aspects:First,the edge of Mo-S itself has abundant active sites.The second is that the Mo-O bonds formed between CeO₂and Mo-S further accelerate the separation and migration of electrons between the catalyst interfaces.Third,the synergistic effect between the S-scheme heterojunction and the Mo-O bond helps to accelerate the separation and migration of light-induced carriers at the catalyst interface.2.A new photocatalyst:graphdiyne（GDY）was successfully prepared by a cross-coupling method,and then a composite catalyst 0.05CIGCS-R with good photocatalytic performance was obtained by using the morphology control strategy.The photocatalytic hydrogen evolution rate（16160μmol/g/h）of 0.05CIGCS-R was 762 and4.56 times higher than that of GDY（21.2μmol/g/h）and Cd S-R（3540μmol/g/h）,respectively.This research focuses are as follows:First,the intrinsic reasons for the significantly improved hydrogen production activity of Cd S-R after the introduction of GDY were explored by photoelectrochemical methods;Secondly,the intrinsic factors affecting the photocatalytic hydrogen evolution activities of different morphologies were further studied by photoelectrochemical methods.Third,the reasons for the slight decrease in the stability of the composite catalysts were analyzed by using the XPS results of the composite materials after photocatalytic hydrogen evolution.3.A stable P（δ^-）-M（δ⁺）-O（δ^-）surface bonding state was cleverly constructed on the surface of NiCo₂O₄by a one-step oxidation-phosphorus doping strategy using NiCo-LDH nanoflowers as a template,and verified by XPS technology.The photocurrent response spectrum and fluorescence spectrum show that the construction of P（δ^-）-M（δ⁺）-O（δ^-）surface bonding state is beneficial to promote the efficient separation of photogenerated carriers.The photocatalytic hydrogen evolution kinetics results show that the hydrogen evolution of 0.3P-NCO with P（δ^-）-M（δ⁺）-O（δ^-）surface bonding state within 5 h is 7.45 and2.38 times that of NiCo-LDH and NiCo₂O₄,respectively.Photocatalytic cycling experiments show that 0.3P-NCO has good durability and stability.4.A"ZIF on MOF"strategy was designed to prepare NiCo-MOF/ZIF catalysts for the first time,and a stable bonding state P（δ^-）-M（δ⁺）-O（δ^-）was formed on the catalyst surface by one-step oxidation-phosphorus doping strategy for NiCo-MOF/ZIF.This novel bonding state has a good inhibitory effect on the recombination of photogenerated carriers.The XPS technique showed that phosphorus doping formed a unique P（δ^-）-M（δ⁺）-O（δ^-）bonding state on the surface of Co O-3Ni O.Fluorescence analysis and photocurrent response spectra showed that the surface P（δ^-）-M（δ⁺）-O（δ^-）formed by phosphorus doping was beneficial to the separation of photogenerated carriers.Photocatalytic hydrogen evolution kinetics verified that the formation of P（δ^-）-M（δ⁺）-O（δ^-）bonding state can accelerate the photocatalytic hydrogen evolution process,and the durability of the catalyst was verified by cycling experiments.