| Photocatalysis can convert solar energy into hydrogen resources via a green way.In order to deeper refine this process,we explored to generate photocatalytic materials with good stability,activity and superb light absorption.In tremendous studies published in the journal,Graphitic carbon nitride,known as g-C3N4 for short,has grown the focus of global researches due to its capabilities such as a good match between its energy level gap and hydrogen production by water decomposition,reliability of chemical reaction and only carbon and nitrogen elements.Inevitably,the material has the shortcomings of poor electrical conductivity and limited specific surface area,and the speed of photocatalytic hydrogen production is not perfect thanks to the speedy recombination of its charge carriers occurrence.Referring to the research inference that have been explored,this paper uses the gas template to bring to nitrogen vacancy and speedy heating and reviving the lone pair electrons in the carbon nitride in the gas template to make improvements.（1）The ultra-fast heating route activates the n-π*electronic transition to enhance the photocatalytic hydrogen production activity.The melamine is heated in a fast heating furnace.During the pyrolysis process,the generated gas is violently released to form a shock wave to collide with the structure of polymer carbon nitride and activate n-π*electronic transition in polymer carbon nitride.The PCN samples prepared show larger specific surface area,stronger light absorption capacity and faster charge transfer.The hydrogen production rate of the sample we obtained through the hydrogen production experiment was 22.52μmol/h,which was 16times that of the comparative sample.It shows that the ultra-fast heating route can successfully increase the rate of photocatalytic hydrogen production.（2）Introducing N vacancies in the gas template improves performance.Ammonium chloride and melamine are mixed in a certain ratio,and heated at 550°C,ammonium chloride undergoes a chemical reaction at this stage,releasing ammonia gas,providing a reducing atmosphere for melamine,and successfully introducing nitrogen vacancies.The introduction of N vacancies makes the material have a larger specific surface area,stronger light absorption capacity and faster charge transfer.Through the hydrogen production experiment,we obtained that the hydrogen production rate of the sample with vacancies was 7.67μmol/h,which was 4.7times that of the original sample,indicating that the use of gas template can successfully introduce vacancies to increase the rate of photocatalytic hydrogen production.（3）One-step ultra-fast heating in a gas atmosphere,the rapid release of the gas creates an impact,which causes a certain deformation of the planar structure of carbon nitride,thereby exciting the lone pair of electrons in the carbon nitride,causing an electronic transition.At the same time,we also observe nitrogen vacancies.The formation of vacancies improves the overall hydrogen production performance.Through the microscopic characterization and composition analysis of the sample,it is found that the separation and recombination rate of photogenerated electrons has slowed down,the light absorption range has been expanded,and the hydrogen production performance of the sample has been improved.Long-term and cycle experiments have also confirmed that the sample has excellent chemical stability. |
