| Today’s society uses fossil fuels as the main source of energy,but the reserves of fossil fuels are getting smaller and smaller and the process of using them is accompanied by a lot of environmental pollution,so there is an urgent need for a new renewable energy source to inject new vitality into the development of society.Hydrogen energy not only has the above advantages but also has other many advantages such as high calorific value and easy storage.Therefore,it has been widely concerned.Among many methods of preparing hydrogen,electrocatalytic water splitting is one very promising way.However,the most of the applicated catalysts with good performance are made of precious metals,hindering its development.Pentlandite is an abundant natural mineral in the earth,which has the low price,easy processing,good electrical conductivity and high electrochemical stability.In addition,pentlandite material has a similar metal structure with [Fe Ni] hydrogenase,and a rich nickel content similar with some nickel-based oxygen evolution reaction(OER)catalyst.Accordingly,it becomes a potential bifunctional water splitting catalyst material.The present studies reported that pentlandite material possess a good catalytic activity for hydrogen evolution reaction(HER).However,its catalytic activity for OER is not satisfactory.Only is the content of nickel in pentlandite material high,it has a good catalytic activity for OER.More importantly,the catalytic mechanism of pentlandite’s OER is still unclear,especially the effect of the special structure of pentlandite on the catalytic activity.And there is no systematic theoretical study on the effect of heteroatom doping on OER,which undoubtedly hinders its large-scale application and development.In this thesis,we focus on the effect of the special structure in pentlandite on its catalytic activity and the effect of heteroatom doping on its catalytic activity,and our studies are as follows:(1)We firstly established the(110)plane of pentlandite as a model catalyst due to its simple chemical environment and complete exposed Fe-Ni heterogenous.The results show that the Fe-Ni bimetallic modulation effect makes the tetrahedral Ni atoms possessing an excellent OER activity while the tetrahedral Fe atoms having a high HER activity.In addition,we established a complete dual-site catalytic cycle path on the(110)plane,and found that the passivation of the Fe sites by hydroxyl groups can improve its OER activity.(2)Subsequently,we constructed the(111)plane of pentlandite which is stable in the experiment.Some transition metal heteroatom as well as nonmetallic heteroatom were selected to replace the octahedral metal atoms or bridging sulfur atoms in pentlandite,respectively.The results showed that Cu,Zn,P,and Se dopant can effectively improve the OER activity of pentlandite.The improved OER activity stems from the modulation of electronic structure for active site by dopant,which can regulate the adsorption strength of the intermediate.In this thesis,we have investigated the effects of Fe-Ni heterostructures,the octahedral metal atoms and the passivated sulfur atoms in pentlandite on the watersplitting reaction by density functional theory.In addition,we also doped the different heteroatoms into pentlandite respectively,analyzed the changes of the catalytic activity of OER,and further investigated the mechanisms.Overall,we explored the structure of pentlandite and proposed a strategy to improve the catalytic activity of OER,which can provide some help for further research and application of pentlandite. |
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