Nanocatalysis and Solar Fuels Research Laboratory, Department of Materials Science & Nanotechnology, Yogi Vemana University, Kadapa, 516005, Andhra Pradesh, India.
Department of Chemistry, School of Advanced Sciences, Vellore Institute of Technology (VIT), Thiruvalam Road, Vellore, 632014, Tamil Nadu, India.
J Environ Manage. 2019 Oct 15;248:109246. doi: 10.1016/j.jenvman.2019.07.017. Epub 2019 Jul 16.
Nano-size photocatalysts exhibit multifunctional properties that opened the door for improved efficiency in energy, environment, and health care applications. Among the diversity of catalyst Quantum dots are a class of nanomaterials having a particle size between 2 and 10 nm, showing unique optoelectrical properties that are limited to some of the metal, metal oxide, metal chalcogenides, and carbon-based nanostructures. These unique characteristics arise from either pristine or binary/ternary composites where noble metal/metal oxide/metal chalcogenide/carbon quantum dots are anchored on the surface of semiconductor photocatalyst. It emphasized that properties, as well as performance of photocatalytic materials, are greatly influenced by the choice of synthesis methods and experimental conditions. Among the chemical methods, photo-deposition, precipitation, and chemical reduction, are the three most influential synthesis approaches. Further, two types of quantum dots namely metal based and carbon-based materials have been highlighted. Based on the optical, electrical and surface properties, quantum dots based photocatalysts have been divided into three categories namely (a) photocatalyst (b) co-catalyst and (c) photo-sensitizer. They showed enhanced photocatalytic performance for hydrogen production under visible/UV-visible light irradiation. Often, pristine metal chalcogenides as well as metal/metal oxide/carbon quantum dots attached to a semiconductor particle exhibit enhanced the photocatalytic activity for hydrogen production through absorption of visible light. Alternatively, noble metal quantum dots, which provide plenty of defects/active sites facilitate continuous hydrogen production. For instance, production of hydrogen in the presence of sacrificial agents using metal chalcogenides, metal oxides, and coinage metals based catalysts such as CdS/MoS (99,000 μmol hg) TiO-Ni(OH) (47,195 μmol hg) and Cu/Ag-TiO nanotubes (56,167 μmol hg) have been reported. Among the carbon-based nanostructures, graphitic CN and carbon quantum dots composites displayed enhanced hydrogen gas (116.1 μmol h) production via overall water splitting. This review accounts recent findings on various chemical approaches used for quantum dots synthesis and their improved materials properties leading to enhanced hydrogen production particularly under visible light irradiation. Finally, the avenue to improve quantum efficiency further is proposed.
纳米尺寸的光催化剂表现出多功能特性，为提高能源、环境和医疗保健应用的效率开辟了道路。在催化剂量子点的多样性中，一类纳米材料具有 2 到 10nm 的粒径，表现出独特的光电特性，仅限于一些金属、金属氧化物、金属硫属化物和基于碳的纳米结构。这些独特的特性源于原始或二元/三元复合材料，其中贵金属/金属氧化物/金属硫属化物/碳量子点锚定在半导体光催化剂的表面上。强调指出，光催化材料的性能和性能受合成方法和实验条件的选择影响很大。在化学方法中，光沉积、沉淀和化学还原是三种最有影响力的合成方法。此外，还突出了两种类型的量子点，即金属基和碳基材料。根据光学、电学和表面特性，将基于量子点的光催化剂分为三类，即(a)光催化剂、(b)共催化剂和(c)光敏剂。它们在可见光/紫外可见光照射下表现出增强的制氢光催化性能。通常，原始金属硫属化物以及附着在半导体颗粒上的金属/金属氧化物/碳量子点通过吸收可见光来增强制氢的光催化活性。或者，提供大量缺陷/活性位点的贵金属量子点有利于连续制氢。例如，在使用金属硫属化物、金属氧化物和贵重金属基催化剂（如 CdS/MoS（99,000μmol hg）TiO-Ni(OH)（47,195μmol hg）和 Cu/Ag-TiO 纳米管（56,167μmol hg）作为牺牲剂的情况下，在存在牺牲剂的情况下生产氢气。在基于碳的纳米结构中，石墨 CN 和碳量子点复合材料通过整体水分解显示出增强的氢气（116.1μmol h）生产。本综述介绍了用于量子点合成的各种化学方法的最新发现及其改善的材料特性，这些特性导致制氢效率提高，特别是在可见光照射下。最后，提出了进一步提高量子效率的途径。
