| With the rapid development of the global economy,energy crisis and environmental pollution are becoming more and more serious.As a clean and efficient energy conversion method,electrocatalysis has received widespread attention.Among them,electrocatalytic oxygen reduction reaction and electrocatalytic hydrogen evolution reaction have a long history of development.The electrocatalytic reduction of oxygen is the cathode reaction of the fuel cell device and the metal-air battery device,and the hydrogen evolution reaction is the cathode reaction of the electrolysis of water,both of them are of great research significance.A lot of works have been invested in the electrode reaction mechanism and catalyst designing,and certain achievements have already been made.Precious metal platinum shows superior catalytic properties for the above two reactions,but the high price and short storage limit the widespread application of platinum.Improving the utilization of platinum and looking for highly efficient non-platinum catalysts have become the research focus.With the rise of carbon materials in recent years,the unique physical and chemical properties of carbon materials and their excellent structure have been favored by scientists.How to further optimize the electronic structure of carbon materials to achieve more efficient catalytic performance,there are still a lot of work to do.In this article,the factors that affect the electrocatalytic performance were carefully analyzed and the structural properties of the carbon material were skillfully controlled to achieve better performance and obtain more efficient energy storage and conversion devices.The author mainly modified the defects in carbon materials with metal atoms to obtain high-performance electrocatalysts for oxygen reduction and hydrogen evolution reactions.This paper mainly includes the following two aspects:(Ⅰ)Nitrogen-doped carbon materials are commonly used as oxygen reduction electrocatalysts.Anchoring metal atoms on carbon through metal-nitrogen-carbon coordination is a useful method for further electronic regulation.Based on this,the author used cesium salt to dope the carbon precursor for the first time,and obtained a cesium-modified nitrogen-doped carbon catalyst.Cesium is classic electron injection material,which significantly reduces the work function of the carbon material surface.The addition of cesium has greatly improved the oxygen reductionperformance of the material.This method of using low work function metal to modify nitrogen-doped carbon is relatively novel and provides new guidance for the development and design of oxygen reduction catalysts in the future.(Ⅱ)Based on the recognition that the carbon-supported platinum catalysts show excellent hydrogen precipitation performance,the author selected platinum atoms to modify the carbon defects,and successfully obtained a hydrogen evolution electrocatalyst with excellent performance.After the defects were manufactured on the carbon paper,the carbon defects were used to adsorb and reduce the platinum atoms without any reducing agents.This method ensured that the platinum atoms directly interact with the carbon defects,avoiding large-scale reunion of platinum.A single-atom platinum catalyst was successfully prepared on a three-dimensional carbon paper and exhibited excellent hydrogen evolution catalytic performance with higher atomic utilization and mass activity compared to commercial platinum carbon.This method provides certain guidance for the design of platinum single atoms and the electronic control of platinum for the hydrogen evolution reaction. |
