以石墨烯作用为导向的多功能石墨烯基复合光催化剂

Multifunctional graphene‐based composite photocatalysts oriented by multifaced roles of graphene in photocatalysis

具有单层二维蜂窝状结构的石墨烯在材料科学和能源转化领域吸引了巨大的研究兴趣.在光催化领域,因其独特的二维平面结构、优异的电荷传输能力、超高的理论比表面积、良好的透光性和化学稳定性,可作为高效的助催化剂,以提高光催化体系的太阳能转换效率.在一些特定的光催化体系中,石墨烯还可以作为大分子光敏剂产生光生电子.近年来,石墨烯基复合光催化剂,如石墨烯-半导体、石墨烯-金属和石墨烯-有机物复合材料,已被广泛应用于光催化水分解制氢、环境净化、二氧化碳还原和选择性有机合成,为缓解能源与环境问题提供了一种有效策略.众所周知,合成方法对石墨烯基复合光催化剂的形貌、尺寸、缺陷结构、表界面性质等影响很大,这些性质与石墨烯基复合光催化剂的催化性能密切相关.因此,探索合适的合成方法制备具有目标功能结构的高效石墨烯基复合光催化剂,具有重要的科学意义.现有的合成方法主要包括:水热/溶剂热法、煅烧法、低温油浴法、溶胶-凝胶法、超声辅助沉积法、微波辅助合成法、电化学沉积法、光化学还原法等.根据概念进行归类,可分为非原位合成法和原位合成法.在非原位合成中,预制的光活性材料的形貌和尺寸保持不变,有利于实现对石墨烯基复合光催化剂微观结构的精确控制,以及对空白光活性组分和复合光催化剂性能进行比较.在原位合成中,石墨烯或其前驱体不仅可以作为二维模板调控纳米晶的成核和生长,合成具有可控形貌和良好界面接触的石墨烯基复合光催化剂,还可以作为三维石墨烯凝胶的自组装模板.此外,氧化石墨烯作为常用的石墨烯前驱体,可以同时作为模板和表面活性剂,灵活调控一些特定复合材料的形貌、尺寸和缺陷结构等.鉴于已有大量综述系统地总结了石墨烯基复合光催化剂的分类、合成方法、性质和应用等,本文先介绍石墨烯基复合光催化剂的优化策略,例如降低石墨烯的缺陷密度、化学掺杂、优化维数、沉积助催化剂、优化界面参数;再以石墨烯在光催化中的基本作用为导向,讨论石墨烯基复合光催化剂的合成.最后,对石墨烯基复合催化剂在光催化领域面临的挑战和优化策略进行了展望,希望为多功能石墨烯基复合光催化剂的合理制备及高效利用提供参考.

Graphene(GR),a single‐layer carbon sheet with a hexagonal packed lattice structure,has displayed attractive potential and demonstrably become the research focus in artificial photocatalysis due to its enchanting properties in enhancing light absorption,electron transfer dynamics,and surface reactions.Currently,numerous efforts have shown that the properties of GR,which are closely correlated to the photocatalytic performance of GR‐based composites are significantly affected by the synthesis methods.Herein,we first introduce the optimization strategies of GR‐based hybrids and then elaborate the synthesis of GR‐based composite photocatalysts oriented by manifold roles of GR in photoredox catalysis,containing photoelectron mediator and acceptor,improving adsorption capacity,regulating light absorption range and intensity,as well as macromolecular photosensitizer.Beyond that,a brief outlook on the challenges in this burgeoning research field and potential evolution strategies for enhancing the photoactivity of GR‐based hybrids is presented and we anticipate that this review could provide some enlightenments for the rational construction and application of multifunctional GR‐based composite photocatalysts.