Sahu Jyotirmayee, Mansingh Sriram, Mishra Bhagyashree Priyadarshini, Prusty Deeptimayee, Parida Kulamani
Centre for Nanoscience and Nanotechnology, Siksha 'O' Anusandhan (Deemed to be University), Bhubaneswar-751030, Odisha, India.
Dalton Trans. 2023 Nov 14;52(44):16525-16537. doi: 10.1039/d3dt02555a.
With the exceptional advantages of safety, greenness, and low cost, photocatalytic HO generation has kindled a wonderful spark, although being severely hampered by the terrible photoinduced exciton recombination, migration, and surface decomposition. Here, employing reflux method, the Cd-Mo-Se quantum dots of varying molar ratios of Cd and Mo were synthesized using thioglycolic acid as the capping ligand to regulate their growth. This type of metal alloying promotes rapid charge migration, improves light harvesting, and reduces the rate of charge recombination. The improved optoelectronic properties and boosted activity of Cd-rich ternary CMSe-1 QDs led to the observed exceptional photocatalytic HO yield of 1403.5 μmol g h (solar to chemical conversion efficiency, 0.27%) under visible light, outperforming the other ternary and Se-based QD photocatalysts. Additionally, CMSe-1 shows 93.6% (2 h) hazardous Cr(VI) photoreduction. The enhanced catalytic performance of CMSe-1 corresponds to effective charge carrier separation and transfer efficiency, well supported by PL, TRPL, and electrochemical measurements. Photocatalytic HO production was also studied under varying experimental conditions and the scavenger test suggests a superoxide radical intermediate 2-step single electron reduction pathway. The catalyst-assisted Cr(VI) reduction is substantiated by the zero-order kinetics as well as the determination of the pH value. The catalyst can be employed for a maximum of four times while retaining its activity, according to the photostability and reusability test outcomes. This research presents interesting approaches for producing ternary QDs and modified systems for efficient photocatalytic HO production and Cr(VI) reduction.
尽管光催化产生羟基（HO）受到严重的光致激子复合、迁移和表面分解的阻碍，但由于其具有安全、绿色和低成本的突出优势，仍引发了人们极大的兴趣。在此，采用回流法，以巯基乙酸作为封端配体，合成了具有不同镉（Cd）和钼（Mo）摩尔比的Cd-Mo-Se量子点，以调控其生长。这种金属合金化促进了电荷的快速迁移，提高了光捕获能力，并降低了电荷复合速率。富含镉的三元CMSe-1量子点改善的光电性能和增强的活性，使其在可见光下的光催化羟基产率达到了1403.5 μmol g⁻¹ h⁻¹（太阳能到化学能的转换效率为0.27%），优于其他三元和基于硒的量子点光催化剂。此外，CMSe-1对有害的Cr(VI)的光还原率为93.6%（2小时）。CMSe-1增强的催化性能对应于有效的电荷载流子分离和转移效率，这得到了光致发光（PL）、时间分辨光致发光（TRPL）和电化学测量的有力支持。还研究了在不同实验条件下的光催化羟基生成，清除剂测试表明存在超氧自由基中间体的两步单电子还原途径。催化剂辅助的Cr(VI)还原通过零级动力学以及pH值的测定得到证实。根据光稳定性和可重复使用性测试结果，该催化剂最多可重复使用四次且仍保持其活性。本研究提出了制备三元量子点以及用于高效光催化羟基生成和Cr(VI)还原的改性体系的有趣方法。
