摘要
在光催化剂上以太阳光为驱动的催化反应是目前太阳能转化和利用的一个有效途径,对解决当前日益严重的环境和能源问题具有重要作用。光催化技术的核心是开发新型光催化剂材料以实现对太阳能的高效利用。卤化铅钙钛矿材料作为一种光电性能优异的半导体材料已经被开创性地应用于光催化领域中,但其差的环境稳定性和元素毒性限制了其未来的发展。以Sn基、Ge基、Bi基和部分过渡金属为主的无铅卤化物钙钛矿有着无毒、带隙可调等优势,有望成为替代铅基卤化物钙钛矿的候选材料。本综述在介绍无铅卤化物钙钛矿结构性质的基础上,总结了不同种类无铅卤化物钙钛矿在光催化领域的应用及性能特性与制备方法,重点阐述了其光催化性能优化策略及环境稳定性的改性方案,最后对无铅卤化物钙钛矿在光催化水解制氢、CO_(2)还原与有机污染物降解等方面的应用进行了展望,并提出了其光催化应用方面的前景与挑战。
With the development of the economy and society,the demand and consumption of traditional fossil energy were increasing rapidly,which produced numerous problems including serious environmental pollution. The photocatalytic reaction could convert solar energy into chemical energy by using semiconductors as the photocatalysts,which might realize H_(2) production and pollutant decomposition. The core of photocatalysis technology was to develop a high-performance photocatalyst for utilizing solar energy efficiently. Lead-free halide perovskites(LFHPs)dominated with Sn,Ge,Bi,and some transition metals had the advantages of low toxicity and adjustable bandgap. These LFHPs were a new generation of photocatalytic materials which showed promising potentials to replace the traditional lead halide perovskites(LHPs)due to their features. In metal halide perovskites(MHPs),the type of MHPs was generally determined by the radius of the composed constituent ion. To satisfy both the Goldschmidt factor and the octahedral factor was necessary for obtaining a stable perovskite crystal structure,which resulted in a limited number of ion species combinations for the formation of halide perovskites. In terms of the optical properties of LFHPs,high photoluminescence quantum yield(PLQY)could be achieved by controlling the crystal grain size,composition,surface treatment process,or other self-modifications. In addition,the multifarious element doping and ligand types might also endow LFHPs with abundant optical properties. For example,the augment of electronegativity of B atoms in ABX_(3) perovskite could narrow the bandgap,and halogen ions could be used for passivation. Additionally,the light absorption range of LFHPs could also be modulated by tuning the structure of the BX_(3) octahedron in LFHPs. After the above modification,the bandgap of LFHPs might match well with the redox potential of the reactants such as CO_(2) and H_(2)O,which could lead to optimized photocatalytic efficiency. Presently,Sn,Ge,Bi,some transition metal elements(such as Ti and Cu),and bimetals were introduced to substitute Pb in LFHPs. Sn element belonged to the same Ⅳ main-group element as Pb,and Sn substituted LFHPs had a narrower bandgap than Pb-based LFHPs,which made Sn-based LFHPs have lower exciton binding energy and longer carrier diffusion length. However,Sn ions were easily oxidized in air,which ultimately restrained the photocatalytic efficiency. A variety of modifications such as oxidation passivation,element doping,and construction of heterojunctions were evoked to optimize the photocatalytic activity. Ge also belonged to the Ⅳ main-group element as Pb. The thermal stability of Ge-based LFHPs was very good,and CsGeI_(3) was thermally stable even at 350 ℃. Some disadvantages of Ge-based LFHPs such as easy oxidation of Ge^(2+) and poor visiblelight absorption limited their application in photocatalysis. As for Bi,the difference of ionic radius between Bi^(2+) and Pb^(2+) was only0.016 nm,which made the Bi substituted sample show prominent properties. For example,Cs_(3)Bi_(2)Br_(9) had good thermal stability and a high photocatalytic synthesis conversion rate. Transition metal-based LFHPs(such as Ti-based and Cu-based)and bimetal-based LFHPs showed longer experimental stability than other LFHPs. Recently,many methods included thermal injection,supersaturation recrystallization,and solvothermal methods were developed to preparing LFHPs. The thermal injection method could monitor the size and morphology of the product by controlling the composition of the halide and the reaction temperature. Unlike thermal injection,supersaturated recrystallization did not require an inert atmosphere and high temperature and could finish the reaction at room temperature. However,it was difficult to control the size of generated crystals due to the fast recrystallization rate at room temperature. As for the solvothermal method,the growth of the crystal was slow and the crystal size was more easily controlled than the recrystallization method. As for the application of halide perovskite materials,poor environmental stability was the main factor restricting the practical application. Accordingly,many strategies were developed to improve the stability of LFHPs:(1)To prepare in a reductive atmosphere to reduce ion oxidation.(2)To add specific ligands to modify the surface of LFHPs.(3)To modulate the morphology of LFHPs by adjusting the synthetic process.(4)To combine LFHPs with other materials to form a heterojunction to achieve improved stability and photocatalytic efficiency. In summary,the research on LFHPs was still in the initial stage although they could overcome the toxicity of LHPs,and key breakthroughs on environmental stability and photocatalytic efficiency should be improved for the practical applications. Post-treatment such as modification should also be considered to improve the stability except for the preparation of LFHPs monomers with high environmental stability(such as all-inorganic LFHPs). In short,LFHPs with good stability should have promising applications in photocatalysis such as H_(2) production,CO_(2) reduction,and pollutant treatment,which might contribute to the current energy and environmental issues.
作者
吴健豪
赵婉
陈默
刘纯希
陈金超
陈智
Wu Jianhao;Zhao Wan;Chen Mo;Liu Chunxi;Chen Jinchao;Chen Zhi(College of Materials and Chemistry,China Jiliang University,Hangzhou 310018,China)
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2022年第1期96-108,共13页
Chinese Journal of Rare Metals
基金
浙江省教育厅一般科研项目(Y202045252)
浙江省高校基本科研业务费专项(2020YW53)
浙江省大学生科研创新活动计划资助项目(2020R409007)
国家级大学生创新创业项目(202010356014)资助。
关键词
无铅卤化物钙钛矿
光催化
光催化制氢
光催化CO_(2)还原
有机物污染物光催化降解
lead-free halide perovskite
photocatalysis
photocatalytic hydrogen production
photocatalytic CO_(2)reduction
photodegradation of organic pollutant
作者简介
吴健豪(1999-),男,浙江金华人,学士,研究方向:环境与能源新材料,E-mail:jianhao_w@126.com;通信作者:陈智,副教授,电话:0571-86835738,E-mail:zchen@cjlu.edu.cn。
