Preparation And Application Of Supported Metal Sulfide Hydrolytic Catalyst For Hydrogen Production

The rapid consumption of fossil fuels has brought about a series of serious environmental and ecological problems.Therefore,hydrogen energy,as a clean,renewable,high energy efficiency and a wide range of sources,is considered to be an ideal alternative to fossil fuels.At present,hydrolysis,photocatalytic water decomposition and electrocatalytic hydrogen production are commonly used.Hydrogen produced by hydrolysis has high purity and easy operation,but high cost.Photocatalytic hydrogen production,which uses semiconductor catalysts and solar energy to decompose water to produce clean fuel H2,has received much attention in the past few decades.Electrochemical hydrogen evolution（HER）is considered to be one of the most promising technologies for developing clean and renewable energy sources.Platinum and other noble metal catalysts commonly used in electrochemical hydrogen evolution are considered to be the most effective electrochemical catalysts.However,its high price and low yield limit its potential for commercialization.In recent years,considerable efforts have been made to develop efficient noble metal-free electrocatalysts based on earth-rich materials such as functionalized carbons,carbonitride compounds,sulfides,phosphating compounds,carbides and nitrides.In particular,sulfides have been used to replace precious metal HER catalysts in focus.Three kinds of sulfide composites were prepared,which were RGO-Molybdenum disulfide（RGO-MOS2）,MWCNTs-MoS2-MoO3 and polyaniline-tin sulfide（PANI-SnS2）.The morphology,size and elemental composition of the composites were investigated by high power transmission and X-ray photoelectron spectroscopy.Electrochemical techniques such as linear sweep voltammetry,cyclic voltammetry and AC impedance were used to study the performance and mechanism of hydrogen production by catalyst hydrolysis,and to explore the performance and effect of catalyst electrocatalytic hydrolysis for hydrogen production with different synthesis ratios.（1）By modifying the classic Hummer method,GO was prepared,and then different proportions of RGO-MoS2 composite materials-were synthesized by weighing different amounts of GO through hydrothermal method.The synthesized samples were denoted as XRGO-MOS2（x=0.1,0.2 and 0.5g,representing the amount of GO）.The characterization results showed that molybdenum disulfide was successfully loaded on the reduced go surface.Electrochemical experiment results show that the electrocatalytic hydrogen evolution activity of the composite material is better than that of the monomer,and the optimized 0.2RGO-MoS2 composite material exhibits strong electrocatalytic hydrogen evolution activity in a wide pH range without the addition of precious metals.In acidic and alkaline medium,the overpotential of O.2RGO-MOS2 at 10 mA cm-2 was 146 mV and 314 mV,respectively.The slope of Tafel in acidic and alkaline media is 51 mV and 80 mV,respectively.（2）MWCNTs-MoS2-MoO3 composites with different proportions were synthesized by hydrothermal method by weighing different quantities of MWCNTs-MoS2-MoO3 composites.The synthesized samples were denoted as xMWCNTs-MoS2-MoO3（x=0.01,0.02 and 0.05g,representing the amount of MWCNTs）.Multiple characterization results showed that MoS2 composite grows on the surface of MWCNTs.Electrochemical experiments showed that there were a large number of S22-bridging and synergistic effects between MWCNTs and MoS2-MoO3 heteroshructures in the 1T/2H phase MoS2,which acted on the photoelectrocatalytic hydrogen evolution reaction（HER）.Near infrared irradiation can increase the charge transport rate.The introduction of MWCNTs and the formation of heterostructures also improved the charge transfer rate and electron hole separation ability of 0.02 MWCNTs-MoS2-MoO3.In acidic medium,0.02 MWCNTs-MoS2-MoO3 had excellent overpotential（68 mV@10 mA cm-2）and Tafel slope（56 mV dec-1）.（3）Polyaniline（PANI）modified tin sulfide nanoplates（PANI-SnS2）were prepared by hydrothermal method.PANI-SnS2 nanocomposites exhibit good photocatalytic activity for hydrogen evolution.The optimized 4%PANI-SnS2（containing 4 wt%PANI）showed the highest electrochemical double-layer capacitance（Cdl）（0.85 mF cm-2）and the lowest Tafel slope（66 mV dec-1）at 0.5 M H2SO4 near infrared irradiation.It is proved that the photothermal and synergistic effects between the heterostructures of stannic sulfide and polyaniline play an important role in promoting the electrocatalytic and photocatalytic hydrogen evolution processes.