【摘要】 氢燃料具有无污染与高质量能量密度的特点使其成为一种重要的清洁能源.通过半导体光催化过程将太阳能转化为氢能,是应对能源与环境问题的理想方案之一.在传统光催化产氢过程中,光生电子可将质子还原生成氢气,而同步产生的光生空穴一般被牺牲剂消耗.虽然反应体系中牺牲剂的添加可以有效提升产氢速率,但是空穴的氧化能力没有得到有效利用.同时,昂贵牺牲剂的使用极大制约了光催化制氢半反应的经济效益和应用前景.通过有机物无氧脱氢反应,同步生成氢气和高附加值有机化合物,不仅实现了电子和空穴的同步利用,而且提升了太阳能的转化效率.尽管这类双功能催化剂近年来已有少量报道,但仍存在光吸收范围窄（紫外-可见光）、掺杂贵金属或载流子分离效率低等问题.因此,开发廉价、高活性、全光谱吸收的催化材料及体系仍是重要且极具挑战性的任务.本文报道了一种非贵金属(MoO_3-x)等离子共振增强的全光谱响应（200-1400 nm）Zn_0.1Cd_0.9S/MoO_3-x S型异质结光催化剂.以乳酸为牺牲剂时,该催化剂可实现高效光解水产氢,其产氢速率高达149.2 mmol·g^-1·h^-1,是纯Zn_0.1Cd_0.9S体系的6倍.此外,当以苯甲醇同时充当电子受体和给体时,可见光（420-780 nm）和近红外光（780-1050 nm）激发均可驱动苯甲醇无氧脱氢,生成苯甲醛和氢气,从而同步有效利用光生电子与空穴.该体系较高的催化效率主要由于:Zn_0.1Cd_0.9S纳米棒和MoO_3-x纳米片之间的界面紧密接触以及内建电场对光生电子转移的动力学促进;S型异质结的构建有效提升了载流子分离效率,同时提高了光生载流子的氧化-还原能力;MoO_3-x纳米片的LSPR效应使得Zn_0.1Cd_0.9S/MoO_3-x复合材料具备了包含紫外-可见-近红外光区域的宽光谱吸收范围.综上,本文系统研究了不同激发能量下产氢过程的反应机理,为理性设计双功能光催化氧化-还原反应体系,实现光催化产氢与精细化学品的同步合成提供了借鉴.更多还原

【Abstract】 Simultaneous generation of H₂ fuel and value-added chemicals has attracted increasing attention since the photo generated electrons and holes can be both employed to convert solar light into chemical energy.Herein,for realizing UV-visible-NIR light driven dehydrogenation of benzyl alcohol（BA） into benzaldehydes（BAD） and H₂,a novel localized surface plasmon resonance（LSPR） enhanced S-scheme heterojunction was designed by combining noble-metal-free plasmon MoO_3-x as oxidation semiconductor and Zn_0.1Cd_0.9S as reduction semiconductor.The photoredox system of Zn_0.1Cd_0.9S/MoO_3-x displayed an unconventional reaction model,in which the BA served as both electron donor and acceptor.The S-scheme charge transfer mechanism induced by the formed internal electric field enhanced the redox ability of charge carriers thermodynamically and boosted charge separation kinetically.Moreover,due to the LSPR effect of MoO_3-x nanosheets,Zn_0.1Cd_0.9S/MoO_3-x photocatalysts exhibited strong absorption in the region of full solar spectrum.Therefore,the Zn_0.1Cd_0.9S/MoO_3-x composite generated H₂ and BAD simultaneously via selective oxidation of BA with high production(34.38 and 33.83 mmol·g^-1 for H₂ and BAD,respectively) upon full solar illumination.Even under NIR light irradiation,the H₂ production rate could up to 94.5 mmol·g^-1·h^-1.In addition,the Zn_0.1Cd_0.9S/MoO_3-x composite displayed effective photo catalytic H₂ evolution rate up to 149.2 mmol·g^-1·h^-1 from water,which was approximate 6 times that of pure Zn_0.1Cd_0.9S.This work provides a reference for rational design of plasmonic S-scheme heterojunction photocatalysts for coproduction of high-value chemicals and solar fuel production.更多还原