PCN/BiOCl Polymer-Based Heterojunction with Rich Chlorine Defects for Photocatalytic Amine Oxidation.

Porous carbon nitride/bismuth oxychloride (PCN/BiOCl-x) polymer-based heterojunction photocatalysts were successfully synthesized via a simple in situ hydrothermal method. A PCN/BiOCl heterojunction with rich chlorine defects is prepared by adjusting the chlorine content of the BiOCl unit in the heterojunction by changing the solvent. The as-prepared catalysts were characterized via BET, SEM, TEM, XRD, XPS and optical testing, and they were used for a photocatalytic amine oxidation reaction. The results indicated that the catalytic performance of the PCN/BiOCl heterojunction was significantly enhanced due to the rich chlorine vacancies in the samples. The enhanced catalytic activity may be attributed to the Z-scheme heterojunction, abundant chlorine defects and large specific surface area. At the same time, the catalyst circulation experiment shows that the PCN/BiOCl heterojunction has good circulation performance.

Construction of a PCN/Fe2O3/CdS double Z-type heterojunction photocatalyst and its application in the oxidative coupling reaction of benzylamine.

In this work, a PCN/Fe2O3/CdS ternary heterojuction photocatalyst was constructed by introducing an appropriate amount of ferric oxide (Fe2O3) and cadmium sulfide (CdS) onto porous carbon nitride (PCN), denoted as PCN/Fe2O3/CdS. In the presence of PCN/Fe2O3/CdS, the turnover frequency value and selectivity of the oxidative coupling reaction of benzylamine were 6740 µmol g-1 h-1 and 99.4%, respectively. The excellent catalytic performance of the PCN/Fe2O3/CdS photocatalyst is attributed to fully exposed active sites due to the porous structure of PCN, improved light utilization efficiency by introduction of Fe2O3 and CdS, and increased mobility of e--h+ pairs by construction of a ternary heterostructure, and was proved by the analysis of its structural and optical properties. According to the substrate scope study and Hammett diagram analysis, the rate determining step of the benzylamine self-coupling reaction photocatalyzed by PCN/Fe2O3/CdS was the condensation of imine and benzylamine into N-benzylidenebenzylamine. The results of the free radical quenching experiment and electron spin resonance tests showed that h+ played a major role in the photoreaction process, followed by ˙O2- and ˙OH. After four photocatalytic reaction cycles, the catalytic performance of the PCN/Fe2O3/CdS heterojunction composite material remained good. Finally, combined with the free radical trapping experiment and energy band structure analysis, a possible double Z-type reaction mechanism was proposed.