Enhanced photocatalytic reduction of Cr(VI) to Cr(III) over g-C3N4 catalysts with Ag nanoclusters in conjunction with Cr(III) quantification based on operando low-field NMR relaxometry,Environmental Science: Nano

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Enhanced photocatalytic reduction of Cr(VI) to Cr(III) over g-C3N4 catalysts with Ag nanoclusters in conjunction with Cr(III) quantification based on operando low-field NMR relaxometry
Environmental Science: Nano ( IF 5.8 ) Pub Date : 2020-08-18 , DOI: 10.1039/d0en00384k
Xingxing Niu _{1,

2,

3,

4,

5} , Jingxian Dong _{1,

2,

3,

4,

5} , Xue Lu Wang _{1,

2,

3,

4,

5} , Ye-Feng Yao _{1,

2,

3,

4,

5}

Affiliation

The design of efficient semiconductor photocatalysts to promote solar-to-chemical conversion remains a tremendous challenge. The present study addresses this issue by loading Ag₉(H₂MSA)₇ and Ag₃₂(MPG)₁₉ nanoclusters (NCs) onto graphitic carbon nitride (g-CN) using a simple impregnation method to form Ag₉NCs/g-CN and Ag₃₂NCs/g-CN hybrid nanocomposites. The performance of the prepared photocatalyst samples investigated for the photocatalytic reduction of aqueous Cr(VI) to Cr(III) under visible-light irradiation is systematically investigated. The proposed nanocomposites exhibit excellent optical absorption properties and efficient separation and migration of photogenerated electron–hole pairs. As a result, the Ag₉NCs/g-CN and Ag₃₂NCs/g-CN nanocomposites provide improved photocatalytic performances relative to that of pristine g-CN photocatalysts with reduction rate constants that are greater than that of pristine g-CN by factors of 2.3 and 2.0, respectively. Furthermore, we for the first time demonstrate the viability of employing operando low-field NMR relaxometry for monitoring the photocatalytic Cr(VI) reduction performance by quantifying the concentration of paramagnetic Cr(III) ions in solution using the transverse relaxation times determined from the Carr–Purcell–Meiboom–Gill pulse sequence. Our study provides new insights for the rational design of high efficiency visible-light photocatalysts, and develops a more efficient method for quantifying the photocatalytic performance of catalysts for transforming heavy metal ions.

中文翻译：

Ag纳米团簇结合基于操作低场NMR弛豫法的Cr（III）定量，在g-C3N4催化剂上增强了Cr（VI）到Cr（III）的光催化还原

设计有效的半导体光催化剂以促进太阳能转化为化学物质仍然是一个巨大的挑战。本研究通过使用简单的浸渍方法将Ag ₉（H ₂ MSA）₇和Ag ₃₂（MPG）₁₉纳米团簇（NCs）加载到石墨氮化碳（g-CN）上以形成Ag ₉ NCs / g-CN来解决此问题。和Ag ₃₂ NCs / g-CN杂化纳米复合材料。研究了制备的光催化剂样品对Cr（VI）水溶液光催化还原为Cr（III）的性能）在可见光照射下进行了系统研究。所提出的纳米复合材料显示出优异的光吸收性能，以及光生电子-空穴对的有效分离和迁移。结果，与原始g-CN光催化剂相比，Ag ₉ NCs / g-CN和Ag ₃₂ NCs / g-CN纳米复合材料提供了改进的光催化性能，其还原速率常数比原始g-CN大，其倍数比分别为2.3和2.0。此外，我们首次展示了通过量化顺磁性Cr（III）的浓度，采用操作性低场NMR弛豫法监测光催化Cr（VI）还原性能的可行性。）溶液中的离子使用从Carr–Purcell–Meiboom–Gill脉冲序列确定的横向弛豫时间。我们的研究为高效可见光光催化剂的合理设计提供了新的见识，并开发了一种更有效的方法来量化催化剂转化重金属离子的光催化性能。

更新日期：2020-09-18

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