离子热后处理C-I共掺杂氮化碳及其光解水制氢性能增强

C-I co-doped carbon nitride with enhanced photocatalytic hydrogen evolution after ionthermal post treatment

以尿素和二氰二胺为原料,碘化离子液为掺杂源,原位共缩聚得到C-I共掺杂氮化碳CNI,进一步进行熔盐离子热后处理得到高结晶度低缺陷的氮化碳CNIS.研究结果表明,对掺杂型氮化碳进行熔盐离子热后处理比常规直接后热处理更有利于碳氮共轭结构优化.500℃熔盐热处理可显著改善增强C-I共掺杂氮化碳催化剂的聚合结晶度和层间紧密堆积性,同时高温离子热处理有利于碳氮共轭杂环微结构重组,降低缺陷位,增强光响应.增大的比表面积和优化的聚合结构促进了光生载流子的快速传输,有效降低了复合率.500℃熔盐热处理产物CNIS的产氢速率与常规后热处理产物CNI相比提高了2.3倍.因此,熔盐离子热处理非金属掺杂氮化碳,能够更有效调控优化催化剂结构,提高光催化制氢性能.

C-I co-dope carbon nitride CNI was synthesized by in situ copolycondensation using urea and dicyandiamine as materials and iodized ionic liquid as doping source.Carbon nitride CNIS with high crystallinity and low defect were obtained by post molten ionthermal treatment.The samples were characterized by XRD,SEM,TEM,FT-IR,XPS,UV-vis,PL etc.Results show that the ionthermal treatment is more beneficial than conventional direct post-thermal treatment method for the structure optimization of the C-I co-dope carbon nitride.500℃molten post-thermal treatment can significantly improve the polymerization crystallinity and interlayer compact stacking of C-I co-dope carbon nitride.Meanwhile,high temperature ionthermal treatment is conducive to the microstructure recombination of carbon-nitrogen conjugated heterocyclic ring,reducing defect and enhancing light response.The increased specific surface area and optimized polymer structure promote the rapid transmission of photon generated carriers and reduce the recombination rate effectively.The hydrogen production rate of CNIS obtained from 500℃molten thermal treatment was 2.3 times higher than that of conventional post-thermal treatment product CNI.Therefore,post thermal treatment of nonmetal doped carbon nitride by molten ionthermal can effectively regulate and optimize the structure of catalyst and improve the performance of photocatalytic hydrogen production.