Das Dimitra, Das Bikram Kumar, Sarkar Ratna, Mukherjee Somnath, Chattopadhyay Kalyan Kumar
School of Materials Science and Nanotechnology, Jadavpur University, 188, Raja S.C. Mallick Road, Kolkata, 700032, India.
Department of Physics, Jadavpur University, 188, Raja S.C. Mallick Road, Kolkata, 700032, India.
Environ Res. 2023 Mar 15;221:115263. doi: 10.1016/j.envres.2023.115263. Epub 2023 Jan 12.
The present work entails the synthesis of thermally modified graphitic carbon nitride (GCN) using a two-step thermal treatment procedure and its subsequent use in the photocatalytic reduction of toxic pollutants such as rhodamine B dye (RhB) and chromium (VI) (Cr(VI)) from aquatic environments. The as-synthesised exfoliated GCN (GCNX) is characterised by X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS), Brunauer-Emmett-Teller analysis (BET), diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). These characterisations helped to elucidate the phase formation, chemical structure, composition, surface area, optical properties, and morphology of the sample. With assistance from a visible light source, GCNX can degrade RhB dye within 30 min in the presence of hydrogen peroxide (HO) and reduce Cr(VI) to Cr(III) in under 2 h in the presence of formic acid (FA/HCOOH). Variations in different catalytic parameters, including catalyst amount, pH of the solution, initial RhB or Cr(VI) concentration, and variation in HO or FA concentration, are performed to inspect their effects on the photodegradation activity of GCNX. Moreover, the GCNX catalyst exhibits impressive stability and reusability. A thorough statistical evaluation follows the response surface methodology to understand the complex interaction between the factors contributing to the catalytic activity. The band alignment of differently functionalised GCN blocks in their pristine form and their HO/FA-adsorbed states is investigated using first-principles calculations to provide a further understanding of the RhB and Cr(VI) reduction mechanisms. The modified GCN can thus be effectively employed as a low-cost material for removing contamination from aquatic environments.
本工作采用两步热处理程序合成热改性石墨相氮化碳（GCN），并将其用于光催化还原水环境中的罗丹明B染料（RhB）和铬（VI）（Cr(VI)）等有毒污染物。通过X射线衍射（XRD）分析、傅里叶变换红外（FTIR）光谱、X射线光电子能谱（XPS）、能量色散X射线光谱（EDS）、布鲁诺尔-埃米特-泰勒分析（BET）、漫反射光谱（DRS）、光致发光光谱（PL）、场发射扫描电子显微镜（FESEM）和透射电子显微镜（TEM）对合成的剥离型GCN（GCNX）进行了表征。这些表征有助于阐明样品的相形成、化学结构、组成、表面积、光学性质和形态。在可见光光源的辅助下，GCNX在过氧化氢（HO）存在下30分钟内可降解RhB染料，在甲酸（FA/HCOOH）存在下2小时内可将Cr(VI)还原为Cr(III)。通过改变不同的催化参数，包括催化剂用量、溶液pH值、初始RhB或Cr(VI)浓度以及HO或FA浓度的变化，来考察它们对GCNX光降解活性的影响。此外，GCNX催化剂表现出令人印象深刻的稳定性和可重复使用性。采用响应面法进行全面的统计评估，以了解影响催化活性的因素之间的复杂相互作用。利用第一性原理计算研究了原始形式及其HO/FA吸附态的不同功能化GCN块的能带排列，以进一步了解RhB和Cr(VI)的还原机理。因此，改性GCN可有效地用作去除水环境中污染物的低成本材料。
