用于改进H_(2)O_(2)制备的1D/0D异质结的ZnIn_(2)S4@ZnO S型光催化剂

1D/0D heterostructured ZnIn_(2)S_(4)@ZnO S‐scheme photocatalysts for improved H2O_(2) preparation

过氧化氢作为一种绿色氧化剂,被广泛应用于食品工业、有机合成、医疗消毒和污水处理等领域.目前,大多数用于工业生产的过氧化氢是通过蒽醌法制备.传统的蒽醌法能耗高、有机副产物多、环境污染严重,因此,利用清洁的太阳能进行半导体光催化生产过氧化氢备受关注.其中,ZnO半导体因其高稳定性、无毒性、良好的生物相容性和合适的导带位置而成为一种潜在的过氧化氢生产材料.然而,单一的ZnO在光催化生产过氧化氢中面临着许多问题,如载流子分离效率低、可见光吸收弱等,从而导致其较低的光催化性能.因此,多种策略被用于解决上述问题,如掺杂非贵金属元素、晶面调控和异质结构构建等.在这些改性策略中,异质结构建被认为是提高光催化性能最有效的方法之一,特别是S型异质结因其较好的氧化还原能力和电子转移特性而备受关注.S型异质结通常由一个氧化型光催化剂和一个还原型光催化剂组成,在两者的接触界面上形成内建电场,促使无用的载流子复合,从而保留更多具有强氧化还原能力的空穴和电子,以此提高异质结光催化性能.ZnIN_(2)S_(4)具有合适的带隙和高导带位置,可以作为还原型光催化剂与ZnO构建S型异质结,从而提高光催化活性.本文首先通过静电纺丝法制备了ZnO纳米纤维,通过化学浴沉积在ZnO纳米纤维上原位生长出ZnIN_(2)S_(4)纳米颗粒,从而合成具有S型异质结结构的ZnO/ZnIN_(2)S_(4)光催化剂.由于ZnO和ZnIN_(2)S_(4)具有相同的金属元素Zn,ZnO纳米纤维中的Zn元素为ZnIN_(2)S_(4)提供了良好的原位生长位点,从而使ZnO和ZnIN_(2)S_(4)之间形成紧密接触,有利于光生载流子的分离和转移.原位XPS结果表明,ZnO/ZnIN_(2)S_(4)复合材料中的In元素和S元素的结合能在光照下降低,而O元素的结合能升高.说明在光照下,ZnO/ZnIN_(2)S_(4)复合材料中ZnO失去电子,而ZnIN_(2)S_(4)得到电子,这与S型异质结的电荷转移机理一致.电子顺磁共振(EPR)结果表明ZnO/ZnIN_(2)S_(4)复合材料能产生比单独ZnO或ZnIN_(2)S_(4)更强的超氧自由基和羟基自由基,说明得益于S型异质结,ZnO/ZnIN_(2)S_(4)复合材料的氧化还原能力得到了提升.此外,电子顺磁共振谱和原位漫反射傅里叶变换红外光谱结果表明,基于ZnO/ZnIN_(2)S_(4)复合材料的光催化双氧水合成反应是一种两步单电子氧还原过程.ZnO/ZnIN_(2)S_(4)复合材料的光催化双氧水生产活性得到显著提升,可以达到928μmol g-1h^(-1),超过ZnO和ZnIN_(2)S_(4)光催化双氧水生产活性的4倍.综上所述,本文合成了低维S型ZnO/ZnIN_(2)S_(4)复合光催化剂,实现过氧化氢生产性能的提升,提供了一种利用相同元素设计和制备高效S型异质结光催化剂的新思路,对异质结在光催化、电催化、太阳能电池等领域的研究起到一定的借鉴作用.

Solar photocatalysis is a promising,green,and sustainable technique for the synthesis of H2O_(2).In this study,low-dimensional ZnO/ZnIn_(2)S_(4) S-scheme heterojunction photocatalysts are fabricated using electrostatic spinning and chemical bath deposition methods for the efficient photocatalytic production of H2O_(2).ZnO nanofibers loaded with 20 wt%ZnIn_(2)S_(4) exhibit a superior H2O_(2) production rate of 928μmol g^(–1)h^(–1),which is more than four times higher than that seen in pristine hexagonal phase ZnO and ZnIn_(2)S_(4).First-principles calculations and in‐situ X-ray photoelectron spectroscopy reveal the charge separation and transfer mechanisms in the S-scheme heterojunction.The construction of the S-scheme heterojunction facilitates the spatial separation of charge carriers,and electrons and holes with higher redox abilities are retained.Photoelectrochemical and photoluminescence tests further show that the formation of an S-scheme heterojunction is beneficial for the separation of photoinduced charge carriers.Electrochemical tests and electron paramagnetic resonance measurements indicate that H2O_(2) production is primarily via a two-step single-electron O_(2) reduction path.This study provides a new approach for the construction of S-scheme heterojunction materials that can efficiently produce H2O_(2) under solar irradiation.