| In the past few decades,serious energy crisis and environmental problems caused by excessive consumption of traditional fossil fuels,such as oil,natural gas and coal are urging the exploration of their sustainable and clean substitutes.In various clean energy sources,hydrogen has been drawn increasing attention for its inexhaustible source,low pollution,high energy density and high efficiency.Compared with traditional hydrogen production methods,photocatalytic and electrocatalytic hydrogen production from water splitting are more clean and sustainable.As an extensive concerned photocatalysts with narrow band gap and suitable band structure,CdS exhibits excellent photocatalytic activity for visible light H2 production.Compared with pure CdS,prospect of composite photocatalyst constructed by CdS and carbon based materials looks more promising,because carbon materials can separate photogenerated electron-hole pairs in time and improve H2 production efficiency.Molybdenum carbide(Mo2C)materials are considered to be promising hydrogen production electrocatalysts owing to their low cost,high chemical stability,and high similarity to platinum-based catalysts.To improve conductivity of Mo2C as well as enhance its electrocatalytic property,the loading of it on carbon matrix has attracted great attention and received satisfactory results because it facilitates fast transfer of electron.In this paper,we prepared CdS based composite photocatalyst and Mo2C based electrocatalyst with N-doped carbon as matrix,and applied them to hydrogen production.The main content of the article is as follows:1.With calcination,an efficient CdS based composite photocatalyst has been synthesized successfully with coordination polymer as precursor,which is constructed by Cd(II)metal ion and 2-mercaptobenzimidazole ligand.During this process,Cd(II)ion and thiol group converts to CdS nanoparticle with the size about 5 to 8 nm,which disperses evenly in nitrogen doped carbon matrix formed by benzimidazole.This reduces the combination of photogenerated electron-hole pair in great extent.Under visible light irradiation,the composite photocatalyst exhibits very excellent H2 production ability as well as perfect stability during H2 production,which does not decay after 30 h.For CdS based composite photocatalysts,calcination temperature exhibits obvious effect on H2 production property.Furthermore,the influence of pyridinic-N,pyrolic-N and quaternary-N on H2 production activity has been discussed in detail.The results illustrate synergistic effect of quaternary-N and pyridinic-N accounts for the improvement of H2 generation efficiency.2.Mo2C based electrocatalyst with three-dimensional N-doped carbon as matrix has been synthesized successfully through a simply one-step solid-state reaction between ammonium molybdate and filter paper at high temperature.Due to its small size,large surface area and high conductivity,this electrocatalyst shows excellent activity in hydrogen evolution reaction(HER).In acid media,its overpotential to achieve a current density of 10 mA·cm-2 is as low as 167 mV,with Tafel slope is only 73 mV·dec-1.Besides these,the electrocatalyst also show large exchange current density,about 0.15 mA·cm-2.Furthermore,it shows excellent durability after 1000 cycles of long-term test,and the catalytic current remains stable over 10 hours at fixed overpotential.The HER of this electrocatalyst was studied and the results illustrate it exhibits a stable hydrogen evolution rate of 44.5 ?mol·h-1 with faradaic efficiency is about 100%. |
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