Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science Chinese Academy of Sciences, No. 71 East Beijing Road, Nanjing 210008, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Environ Sci Technol. 2021 Oct 5;55(19):13132-13141. doi: 10.1021/acs.est.1c04026. Epub 2021 Sep 14.
Microbial-mediated transformation of anthropogenic Cd controls its distribution, bioavailability, and potential risks. However, the processes readily form CdS nanoparticles (CdS-NPs), which exhibit dissolution behavior different from that of larger sized particles. Here, we investigated the effects of morphologies and facets of CdS-NPs on their photoinduced dissolution. Three CdS-NPs, CdS-sphere, CdS-rod, and CdS-sheet, and one nanosized biogenic CdS (Bio-CdS) were synthesized with different dominant facets of {101}, {100}, {001}, and {111} and thus distinct surface chemistry. As explored by HRTEM, EPR, and DFT calculations, photogenerated e/h pairs were more likely to generate on CdS-sheet surfaces due to higher surface energies and a narrower band gap, facilitating the formation of •OH and thereby faster dissolution ( = 6.126-6.261 × 10 h). The wider band gaps of CdS-sphere and CdS-rod caused less formation of O and •OH, leading to slower oxidative dissolutions ( = 0.090-0.123 and 2.174-3.038 × 10 h, respectively). Given the similar surface energy as that of CdS-sheet, the dissolution rate of Bio-CdS was close to that of CdS-rod and CdS-sheet, which was 1.6-3.5 times faster than that of larger sized CdS, posing higher environmental risks than thought. Altogether, this work revealed the facet effects on the dissolution of CdS-NPs, manifesting a deeper understanding of metal sulfides' environmental behaviors.
微生物介导的人为 Cd 的转化控制其分布、生物可利用性和潜在风险。然而，这一过程很容易形成 CdS 纳米粒子（CdS-NPs），其溶解行为与较大粒径的颗粒不同。在这里，我们研究了 CdS-NPs 的形态和晶面效应对其光诱导溶解的影响。我们用不同的主导晶面{101}、{100}、{001}和{111}合成了三种 CdS-NPs，即 CdS 球、CdS 棒和 CdS 片，以及一种纳米级生物 CdS（Bio-CdS），它们具有不同的表面化学性质。通过 HRTEM、EPR 和 DFT 计算发现，由于较高的表面能和较窄的能带隙，光生电子/空穴对更容易在 CdS 片表面产生，从而更容易形成•OH，导致更快的溶解（=6.126-6.261×10 h）。CdS 球和 CdS 棒较宽的能带隙导致较少的 O 和•OH 的形成，从而导致较慢的氧化溶解（分别为=0.090-0.123 和 2.174-3.038×10 h）。由于与 CdS 片具有相似的表面能，Bio-CdS 的溶解速率与 CdS 棒和 CdS 片相近，比较大粒径的 CdS 快 1.6-3.5 倍，这表明其环境风险比预期的要高。总的来说，这项工作揭示了晶面对 CdS-NPs 溶解的影响，更深入地了解了金属硫化物的环境行为。
