Wu Mengjiao, Lv Chengpu, Xiong Yuling, Li Wenglong, Lin Yuangui, Li Jing, Yu Fei, Yuan Huan, You Biao, Zhang Qiuping, Xu Ming
Key Laboratory of Information Materials of Sichuan Province, College of Electronic and Information, Southwest Minzu University, Chengdu 610041, China.
Key Laboratory of Biopesticide and Chemical Biology, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
J Adv Res. 2025 Jun 10. doi: 10.1016/j.jare.2025.06.027.
Heterostructured photocatalysts have shown an enormous potential in photocatalytic degradation of organic pollutants in wastewater. However, the efficacy of such heterojunction on the photocatalytic degradation behaviors has not yet been fully revealed.
This work aims to demonstrate a specific photocatalytic degradation behavior of ZnO-based heterostructured nanocomposites toward methyl orange (MO) and methylene blue (MB) dyes based on a systematically comparative investigation for their physical and chemical properties.
A series of low-cost and efficient ZnO-based heterostructured nanocomposite photocatalysts including ZnO/CuO, ZnO/TiO and ZnO/SnO with 3 and 10 mol% of CuO/TiO/SnO were synthesized by a simple strategy to combine the modified polymer-network gel and traditional sol-gel methods. The physical and chemical properties were analyzed using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), X-ray photoelectron spectra (XPS), ultraviolet-visible (UV-Vis) absorption spectra, photoluminescence (PL), surface photovoltage (SPV), electrochemical impedance spectroscopy (EIS) and zeta potential.
Owing to the fast interfacial charge transfer at the heterojunction, all the three ZnO-based nanocomposite catalysts exhibited higher efficient separation of photogenerated electrons and holes, delivering an enhanced photocatalytic activity for the degradation of organic dyes compared with pure ZnO. Three photocatalysts of ZnO/3 %-CuO, ZnO/3 %-TiO and ZnO/10 %-SnO (marking as ZC3, ZT3 and ZS10, respectively) were capable of achieving the complete degradation of 4 mg/L concentration of MB dye within 50 min, and the first two could degrade MO within 80 min. However, the degradation rate of MO by ZS10 became significantly slower. For MO and MB degradation, the active species of photogenerated holes (h) and superoxide radicals (·O) play the predominant roles, respectively, followed by hydroxyl radicals (·OH). The differences in heterojunction configuration and dominant active species result in a specific photocatalytic degradation behavior of ZnO-based composite nanostructures.
The generation of the active species are influenced by the heterojunction configurations, of which the essence is that the different band alignments can results in the differences of interfacial charge transfer behaviors, and thus selective generation of the active species such as h, ·O and ·OH. Importantly, this work offers a fundamental understanding for specific photocatalytic degradation of the different heterojunction nanostructures towards the different organic dyes.
异质结构光催化剂在光催化降解废水中的有机污染物方面显示出巨大潜力。然而，这种异质结在光催化降解行为方面的功效尚未得到充分揭示。
本研究旨在通过对基于氧化锌（ZnO）的异质结构纳米复合材料的物理和化学性质进行系统的对比研究，来证明其对甲基橙（MO）和亚甲基蓝（MB）染料的特定光催化降解行为。
采用一种简单的策略，将改性聚合物网络凝胶法与传统溶胶 - 凝胶法相结合，合成了一系列低成本且高效的基于ZnO的异质结构纳米复合光催化剂，包括含3 mol%和10 mol%氧化铜（CuO）/二氧化钛（TiO）/氧化锡（SnO）的ZnO/CuO、ZnO/TiO和ZnO/SnO。使用X射线衍射（XRD）、场发射扫描电子显微镜（FESEM）、透射电子显微镜（TEM）、X射线光电子能谱（XPS）、紫外可见（UV - Vis）吸收光谱、光致发光（PL）、表面光电压（SPV）、电化学阻抗谱（EIS）和zeta电位对其物理和化学性质进行分析。
由于异质结处快速的界面电荷转移，所有三种基于ZnO的纳米复合催化剂均表现出光生电子和空穴的更高效率分离，与纯ZnO相比，对有机染料的降解具有增强的光催化活性。三种光催化剂ZnO/3%-CuO、ZnO/3%-TiO和ZnO/10%-SnO（分别标记为ZC3、ZT3和ZS10）能够在50分钟内实现4 mg/L浓度的MB染料的完全降解，前两种能够在80分钟内降解MO。然而，ZS10对MO的降解速率明显变慢。对于MO和MB的降解，光生空穴（h）和超氧自由基（·O）分别起主要作用，其次是羟基自由基（·OH）。异质结结构和主要活性物种的差异导致了基于ZnO的复合纳米结构的特定光催化降解行为。
活性物种的产生受异质结结构的影响，其实质是不同的能带排列会导致界面电荷转移行为的差异，从而选择性地产生h、·O和·OH等活性物种。重要的是，这项工作为不同异质结纳米结构对不同有机染料的特定光催化降解提供了基本的理解。
