物理化学学报

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金属碳化钨与液相染料光敏剂协同促进光催化制氢

雷永刚1,2, 赵天宇3, 黄锦鸿4, 张颖贞1, 臧雪瑞5, 李晓1, 蔡伟龙1,2, 黄剑莹1,2, 胡军3, 赖跃坤1,2   

  1. 1 福州大学石油化工学院, 化肥催化剂国家工程研究中心(NERC-CFC), 福州 350116;
    2 清源创新实验室, 福建 泉州 362801;
    3 西北大学化工学院, 西安 710069;
    4 明志科技大学生化工程技术研发中心, 台湾 新北 24301;
    5 中国石油大学(华东)储运与建筑工程学院, 山东 青岛 266580
  • 收稿日期:2022-06-04 修回日期:2022-06-28 录用日期:2022-06-29 发布日期:2022-07-01
  • 通讯作者: 赖跃坤 E-mail:yklai@fzu.edu.cn
  • 基金资助:
    国家自然科学基金(22075046,51972063,21676216,21501127,51502185);国家重点研发计划(2019YFE0111200);福建省杰出青年基金(2020J06038);福建省自然科学基金(2019J01256);111项目(D17005);中国博士后科学基金(前期站,2019TQ0061);陕西省教育厅专项(20JC034)资助.KimHoongNg感谢台湾科技部(MOST)和明志科技大学(MCUT)的财政支持(MOST-110-2222-E-131-004-,VK000-1300-111)

Metallic Tungsten Carbide Coupled with Liquid-Phase Dye Photosensitizer for Efficient Photocatalytic Hydrogen Production

Yonggang Lei1,2, Tianyu Zhao3, Kim Hoong Ng4, Yingzhen Zhang1, Xuerui Zang5, Xiao Li1, Weilong Cai1,2, Jianying Huang1,2, Jun Hu3, Yuekun Lai1,2   

  1. 1 National Engineering Research Center of Chemical Fertilizer Catalyst(NERC-CFC), College of Chemical Engineering, Fuzhou University, Fuzhou 350116, China;
    2 Qingyuan Innovation Laboratory, Quanzhou 362801, Fujian Province, China;
    3 School of Chemical Engineering, Northwest University, Xi'an, 710069, China;
    4 R&D Center of Biochemical Engineering Technology, Ming Chi University of Technology, New Taipei 24301, Taiwan, China;
    5 College of Pipeline and Civil Engineering, China University of Petroleum(East China), Qingdao 266580, Shandong Province, China
  • Received:2022-06-04 Revised:2022-06-28 Accepted:2022-06-29 Published:2022-07-01
  • Contact: Yuekun Lai E-mail:yklai@fzu.edu.cn
  • Supported by:
    The project was supported by the National Natural Science Foundation of China (22075046, 51972063, 21676216, 21501127, 51502185), National Key Research and Development Program of China (2019YFE0111200), Natural Science Funds for Distinguished Young Scholar of Fujian Province (2020J06038), Natural Science Foundation of Fujian Province (2019J01256), 111 Project (D17005), China postdoctoral science foundation (Pre-station, 2019TQ0061), Special Project of Shaanxi Provincial Education Department (20JC034). Kim Hoong Ng thanks Ministry of Science and Technology (MOST), Taiwan, and Ming Chi University of Technology (MCUT) for the financial supports (MOST-110-2222-E-131-004-, VK000-1300-111).

摘要: 使用WC作为光催化材料通过水还原制氢很常见,但它通常需要与有效的光吸收剂协同才能产生有意义的光催化活性。这可归因于WC的窄带隙,导致水的氧化还原能力不足。有趣的是,我们的研究通过一种新型固液光催化体系克服了这种限制,该体系将裸WC光催化剂与液相光敏赤藓红B (ErB)相结合。这种概念的提出消除了将WC耦合到光吸收半导体的需要,这通常需要繁琐的程序来获得适当的功能化光催化复合材料。实验结果表明,在可见光(λ=520 nm)照射下,所提出的固液光催化体系产生了显著的氢气,然而,只有在三乙醇胺(TEOA)作为牺牲试剂的共同存在下。显然,仅加入WC和ErB的空白实验在典型的光催化条件下表现出几乎为零的光催化活性和无法测量的H2生成。在光照TEOA溶液中仅存在ErB或WC的光反应中也观察到类似的活性。这些空白实验证实了所有三种成分的重要性,即WC、ErB和TEOA,它们分别作为光催化剂、光吸收剂和牺牲试剂,在我们提出的体系中产生有意义的H2。值得注意的是,在我们的调查中系统地研究了三个关键参数,即pH值、ErB和WC浓度的影响。发现H2生成的最佳pH值为8,稍微改变到更碱性或酸性条件会降低体系的光催化活性。在pH<8时,部分TEOA将发生部分质子化,从而失去其在光催化体系中作为牺牲试剂的活性。当pH值增加到超过8时,反应介质中的低质子浓度也会扰乱热力学驱动,导致体系产生的H2受到抑制。同时,发现最佳ErB浓度为1 mmol·L-1,从最佳点降低或增加ErB浓度均不利于H2的产生。ErB浓度较低的体系(<1 mmol·L-1),在吸光上不足以满足体系的礼用,而较高浓度(>1 mmol·L-1 ErB)的体系,会引起明显的散射效应,组织光穿透反应溶液。相反,WC的浓度与H2的生成呈稳定的正相关,在加入12 mmol·L-1 WC的体系中,H2的生成量最高。在最佳条件下,成功生成了66 μmol∙h-1 H2,AQE略高为6.6%在520 nm处,这归因于ErB-TEOA-WC在所提出的体系中的协同作用。光电化学评估证实了ErB、TEOA和WC之间的相互作用,从而降低了阻抗,同时提高了体系中的电荷利用率。因此,还记录到了极好的H2转换数(TON)为15,在至少20 h的连续反应中具有难以察觉的活性衰减。对于机理,密度泛函理论(DFT)计算进一步证实了W和C空位在H2生成中的主要作用,这归因于他们提供的产品解吸,在光反应期间提高转化速率。从这些发现中得出结论,我们提出的新型WC/ErB/TEOA体系在液固光催化体系提供了一种更容易从水中产生H2的策略,这为金属碳化物光催化剂避免选择繁琐的光吸收剂耦合。

关键词: 液相, WC, 赤藓红B, 三乙醇胺, 光催化, 制氢

Abstract: Tungsten carbide (WC) is commonly used as a photocatalytic material for hydrogen production via water reduction. However, it is often combined with an effective photoabsorber to provide sufficient photoactivity. This is attributed to the narrow band gap of WC, which leads to an inadequate redox capability for water reduction. Notably, this limitation was overcome using a novel solid-liquid photocatalytic system that compliments bare WC photocatalysts with liquid-phase photosensitizing erythrosine B (ErB). The proposed concept eliminates the need to couple WC with photoabsorbing semiconductors, which often requires tedious procedures for the proper functionalization of photocatalytic composites. The experimental results indicated significant hydrogen production from the proposed solid-liquid photocatalytic system under irradiation with visible light (λ = 520 nm); however, only in the presence of triethanolamine (TEOA) as a sacrificial reagent. Evidently, a blank experiment with only WC and ErB under typical photoreaction conditions exhibited nearly zero photoactivity and the production of H2 was undetected. Similarly, nonactivity was observed for the photoreaction in the presence of ErB or WC in the irradiated TEOA solution. These blank experiments confirmed the significance of all three components, namely WC, ErB, and TEOA, which functioned as the photocatalyst, photoabsorber, and sacrificial reagent, respectively, for suitable H2 production in the proposed system. The effects of three critical parameters, such as pH, ErB concentration, and WC concentration, were systematically investigated. The optimum pH for H2 production was 8, with a slight variation to more basic or acidic conditions reducing the photoactivity of the system. At pH < 8, part of TEOA undergoes partial protonation, thereby losing its activity as a sacrificial reagent in the photocatalytic system. As the pH increased to > 8, the low proton concentration in the reaction medium perturbed the thermodynamic drive, leading to suppressed H2 production. The optimum ErB concentration was 1 mmol·L−1, and decreasing or increasing the ErB concentration from the optimal point was detrimental to H2 production. The diluted system (ErB concentration < 1 mmol·L−1) provided insufficient sensitizing agents, whereas the concentrated system (> 1 mmol·L−1 ErB) induced significant scattering effects that prevent light from penetrating into the reactive liquid phase. Conversely, the WC concentration exhibited a positive correlation with H2 production in a steady manner, and the highest H2 production measured by the system was at a WC concentration of 12 mmol·L−1. Under optimum conditions, 66 μmol∙h−1 of H2 was successfully produced, with a slightly higher apparent quantum efficiency (AQE) of 6.6% at 520 nm, which was attributed to the synergism of ErB-TEOA-WC in the proposed system. The photoelectrochemical evaluation confirmed the positive interactions between ErB, TEOA, and WC, which caused reduced impedance while improving charge utilization in the system. Consequently, an excellent H2 turnover number (TON) of 15 was achieved with negligible activity decay for at least 20 h of reaction. Density functional theory (DFT) calculations confirmed the major roles of W- and C-vacant sites in H2 production, which were attributed to their enhanced product desorption that facilitates high turnover rates during photoreactions. In conclusion, the proposed novel liquid-solid photocatalytic WC/ErB/TEOA system provides more facile photo-derived H2 energy from water, which circumvents the tedious photoabsorber coupling of metal carbide photocatalysts.

Key words: Liquid-phase, WC, Erythrosine B, Triethanolamine, Photocatalysis, H2 production

MSC2000: 

  • O643