物理化学学报

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Ni2P-NiS双助剂促进g-C3N4光催化产氢动力学

雷卓楠1, 马心怡1, 胡晓云2, 樊君1, 刘恩周1   

  1. 1 西北大学化学工程学院/西安特种能源材料重点实验室, 西安 710069;
    2 西北大学物理学院, 西安 710069
  • 收稿日期:2021-10-29 修回日期:2021-11-12 录用日期:2021-11-24 发布日期:2021-11-24
  • 通讯作者: 樊君, 刘恩周 E-mail:liuenzhou@nwu.edu.cn;fanjun@nwu.edu.cn
  • 基金资助:
    国家自然科学基金(21676213,11974276,22078261),陕西省自然科学基础研究计划项目(2020JM-422)资助

Enhancement of Photocatalytic H2-evolution Kinetics through the Dual Cocatalyst Activity of Ni2P-NiS-decorated g-C3N4 Heterojunctions

Zhuonan Lei1, Xinyi Ma1, Xiaoyun Hu2, Jun Fan1, Enzhou Liu1   

  1. 1 School of Chemical Engineering/Xi'an Key Laboratory of Special Energy Materials, Northwest University, Xi'an 710069, China;
    2 School of Physics, Northwest University, Xi'an 710069, China
  • Received:2021-10-29 Revised:2021-11-12 Accepted:2021-11-24 Published:2021-11-24
  • Contact: Jun Fan, Enzhou Liu E-mail:liuenzhou@nwu.edu.cn;fanjun@nwu.edu.cn
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (21676213, 11974276, 22078261), Natural Science Basic Research Program of Shaanxi (2020JM-422).

摘要: 本文通过简单的一步水热法得到Ni2P-NiS双助催化剂,之后采用溶剂蒸发法将Ni2P-NiS与g-C3N4纳米片结合构建获得无贵金属的Ni2P-NiS/g-C3N4异质结。研究结果表明,优化后的复合材料具有良好的光催化产氢活性,其产氢速率最高可到6892.7 μmol·g-1·h-1,分别为g-C3N4(150 μmol·g-1·h-1)、15% NiS/g-C3N4(914.5 μmol·g-1·h-1)和15% Ni2P/g-C3N4(1565.9 μmol·g-1·h-1)的46.1、7.5和4.4倍。这主要归因于Ni2P-NiS相比Ni2P和NiS单体具有更好的载流子转移能力,其与g-C3N4形成的肖特基势垒能有效促进光生载流子在二者界面上的分离,同时Ni2P-NiS能进一步降低析氢过电势,进而显著增强了表面析氢反应动力学。本研究为开发稳定、高效的非贵金属产氢助剂提供了实验基础。

关键词: Ni2P-NiS, g-C3N4, 助催化剂, 肖特基结, 光催化分解水

Abstract: With rapid industrialization, issues pertaining to the environment and energy have become an alarming concern. Photocatalytic water splitting is considered one of the most promising green technologies capable of resolving these issues, as it can convert solar energy into chemical energy and have a positive impact on the realization of "carbon neutrality". Current research focuses on the development of highly efficient catalysts to improve the photocatalytic H2-production activity. Transition metal phosphides and sulfides are often used as photocatalysts owing to their low H2-evolution overpotential and excellent electrical conductivity. Among them, Ni2P and NiS have generally been used independently during photocatalytic H2 production; however, it is necessary to study the synergistic effect when they are combined as a dual cocatalyst. In this work, we successfully prepared a Ni2P-NiS dual cocatalyst for the first time via a simple hydrothermal method using red phosphorus (RP) and thioacetamide (C2H5NS) as the sources of P and S. Ni2P-NiS was then introduced to the surface of g-C3N4 nanosheets through solvent evaporation to create a Ni2P-NiS/g-C3N4 heterojunction. Furthermore, X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), ultraviolet-visible spectrophotometry (UV-Vis), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), linear sweep voltammetry (LSV), Mott-Schottky (M-S), and electrochemical impedance spectroscopy (EIS) were used to reveal the crystal structures, morphologies, element compositions, and photoelectric characteristics of the samples; thus, it was demonstrated that Ni2P-NiS was successfully deposited on the surface of g-C3N4 and that together they exhibited better activity than their monomers. Moreover, the optimized 15% Ni2P-NiS/g-C3N4 composite exhibits a H2 generation rate of 6892.7 μmol·g-1·h-1, which is about 46.1, 7.5 and 4.4 times higher than that of g-C3N4 (150 μmol·g-1·h-1), 15% NiS/g-C3N4 (914.5 μmol·g-1·h-1), and 15% Ni2P/g-C3N4 (1565.9 μmol·g-1·h-1), respectively. In addition, photoelectric performance tests show that Ni2P-NiS/g-C3N4has a stronger photocurrent intensity, smaller charge-transfer resistance, more positive H2-evolution overpotential, and better charge-separation ability than the individual components (i.e., Ni2P and NiS), suggesting that the coexistence of Ni2P and NiS can further boost the activity of g-C3N4 during H2evolution compared with their monomers. This is mainly due to the Schottky barrier effect between Ni2P-NiS nanoparticles and g-C3N4nanosheets, which can greatly promote charge separation and charge transfer at their interface. Additionally, Ni2P-NiS can reduce the H2-evolution overpotential, leading to the increased surface kinetics of H2 evolution. This work offers a promising approach to obtaining a highly active and stable noble-metal-free dual cocatalyst for photocatalytic H2 production.

Key words: Ni2P-NiS, g-C3N4, Cocatalyst, Schottky barrier, Photocatalytic water splitting

MSC2000: 

  • O643