物理化学学报 >> 2024, Vol. 40 >> Issue (11): 2406019.doi: 10.3866/PKU.WHXB202406019

所属专题: 太阳燃料制备

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两步焙烧法制备大比表面积和结晶性增强超薄g-C3N4纳米片及其高效光催化产H2O2

陈恒, 聂龙辉*(), 徐凯, 杨毅琼, 方彩红   

  1. 湖北工业大学材料与化学工程学院, 武汉 430068
  • 收稿日期:2024-06-17 修回日期:2024-07-18 录用日期:2024-07-18 发布日期:2024-10-14
  • 通讯作者: Email: nielonghui@mail.hbut.edu.cn; Tel.: +86-27-87280460 (聂龙辉)
  • 基金资助:
    国家自然科学基金(51572074); 毒品分析及禁毒技术公安部重点实验室开放课题(YNPL-B2021002)

Remarkable Photocatalytic H2O2 Production Efficiency over Ultrathin g-C3N4 Nanosheet with Large Surface Area and Enhanced Crystallinity by Two-Step Calcination

Heng Chen, Longhui Nie*(), Kai Xu, Yiqiong Yang, Caihong Fang   

  1. School of Materials and Chemical Engineering, Hubei University of Technology, Wuhan 430068, China
  • Received:2024-06-17 Revised:2024-07-18 Accepted:2024-07-18 Published:2024-10-14
  • Contact: Email: nielonghui@mail.hbut.edu.cn; Tel.: +86-27-87280460 (Longhui Nie)
  • Supported by:
    the Natural Science Foundation of China(51572074); Open Fund of Key Laboratory of Drug Analysis and Anti-drug Technology of the Ministry of Public Security(YNPL-B2021002)

摘要:

以水和氧气为原料,光催化产过氧化氢(H2O2)具有绿色、清洁的特点而受到广泛关注。针对氮化碳(g-C3N4)本征光催化活性低的问题,本文采用两步热聚合法制备了具有大比表面积和结晶性增强的超薄g-C3N4纳米片光催化剂。煅烧条件对g-C3N4的结构属性和催化性能有显著影响。两步焙烧和1 ℃·min-1最佳升温速率制备的样品(CN-T-1)表现出显著提高的光催化产H2O2效率(3177.0 µmol·g-1·h-1),为一步焙烧和1 ℃·min-1升温速率制备的样品(CN-O-1)(858.6 µmol·g-1·h-1)的3.7倍,高于文献报导的纯g-C3N4产H2O2效率。CN-T-1在5次循环使用中H2O2产率先略有下降,后基本保持不变,表现出良好的稳定性。相较于CN-O-1,CN-T-1增强的催化性能归因于更大的比表面积、增强的结晶性、更高氧吸附能力和光生载流子分离效率、更长的载流子寿命,以及超薄片层使其具有更大的带隙(3.07 eV, 比CN-O-1大+0.26 eV)和更正的价带位置。•O2-自由基被证实为主要的活性物种。CN-T-1光催化产H2O2被证实为两步单电子ORR路径(O2 + e- → •O2- → H2O2)。

关键词: 光催化, H2O2制备, g-C3N4纳米片, 光催化机理

Abstract:

The generation of hydrogen peroxide (H2O2) from water and oxygen redox reaction by photocatalysis has acquired increasing attention owing to its green and clean properties. Aiming at the low intrinsic photocatalytic activity of carbon nitride (g-C3N4), here, an ultrathin g-C3N4 nanosheet photocatalyst with a large surface area and enhanced crystallinity was fabricated by a two-step thermal polymerization technique. The calcination parameters showed a significant impact on the structural properties and catalytic performance of g-C3N4. The remarkable H2O2 yield (3177.0 µmol·g-1·h-1) of CN-T-1 (by two-step calcination, 1 ℃·min-1 optimal heating rate) was 3.7 times that (858.6 µmol·g-1·h-1) of CN-O-1 (by one-step calcination, 1 ℃·min-1 heating rate) and higher than those of pure g-C3N4 in literature. Most of the H2O2 yield for CN-T-1 remained after five cycles, showing good stability. The enhanced catalytic performance of CN-T-1 than CN-O-1 is owing to its larger specific surface area, enhanced crystallinity, higher oxygen adsorption ability and photogenerated carrier separation efficiency, longer lifetime of carriers, and slightly larger bandgap (3.07 eV, +0.26 eV bigger than CN-O-1) with more positive valence band position owing to ultrathin layers. The •O2- radicals were verified to be the primary active species. A two-step single electron ORR pathway (O2 + e- → •O2- → H2O2) was confirmed for H2O2 production over CN-T-1.

Key words: Photocatalytic, H2O2 production, g-C3N4 nanosheet, photocatalytic mechanism