It is well known that graphite-like carbon nitride (g-CN) is a good photocatalyst for in-situ the production of HO. However, how to activate HO generating the strong oxidizing ·OH is the key factor to affect the degradation of pollutants. In this paper, the layered g-CN nanosheets were prepared by using urea and HO with different mass ratios and calcined in Muffle furnace by one-step synthesis method. The morphology, composition and structure of photocatalysts were analyzed, indicating that the as-prepared L-g-CN-7 had abundant edge regions in comparison with L-g-CN made by solid urea. The photocatalytic performance of g-CN nanosheets was investigated with atrazine (ATZ) as the target pollutant in water. The results revealed that the prepared L-g-CN-7 exhibited the best photocatalytic activity in visible light (λ ≥ 420 nm). The degradation of 1.0 mg/L ATZ reached over 96% after 3 hours and the photocatalytic degradation rate constant (k) was 6.8 times than that of L-g-CN photocatalyst. In addition, under the same conditions, the HO production of L-g-CN-7 was 4.5 times than that of L-g-CN photocatalyst. Based on the capture experiments of free radicals, it was found that the contribution rate of ·OH in L-g-CN-7 photocatalytic increased to 17 % compared to 4 % of L-g-CN photocatalyst during the degradation of ATZ. The ·OH quantitative experiment indicated that the L-g-CN-7 photocatalyst could obviously activate HO to generate ·OH and the amount of ·OH was 2.5 times than that of the L-g-CN photocatalyst. More importantly, a large amount of terminal-NH (14.6 %) in L-g-CN-7 was measured by the XPS, FT-IR and zeta potential. The additive HO adsorption experiment in the dark was used to confirm terminal-NH sites of L-g-CN-7 photocatalyst, which was beneficial to adsorb and activate HO. The results illustrated that the L-g-CN-7 photocatalyst with rich edge regions and terminal-NH had the characteristics of in-situ the activation of HO to generate ·OH. The findings suggest that designing and developing efficient g-CN photocatalysts pave a new avenue for activating in situ self-synthesizing HO and the removal of atrazine in water.

中文翻译：

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制备层状 g-C3N4 纳米片用于高效光催化降解莠去津：洞察 H2O2 末端 NHx 原位活化

众所周知，类石墨氮化碳（g-CN）是原位生产 H2O 的良好光催化剂。然而，如何激活H2O产生强氧化性·OH是影响污染物降解的关键因素。本文以不同质量比的尿素和H2O为原料，采用一步合成法制备了层状g-CN纳米片，并在马弗炉中煅烧。对光催化剂的形貌、组成和结构进行分析表明，与固体尿素制备的Lg-CN相比，所制备的Lg-CN-7具有丰富的边缘区域。以莠去津（ATZ）为目标污染物，研究了 g-CN 纳米片的光催化性能。结果表明，所制备的Lg-CN-7在可见光（λ≥420 nm）下表现出最佳的光催化活性。 1.0 mg/L ATZ 3小时后降解率达到96%以上，光催化降解速率常数（k）是Lg-CN光催化剂的6.8倍。此外，在相同条件下，Lg-CN-7的H2O产量是Lg-CN光催化剂的4.5倍。通过自由基捕获实验发现，在ATZ降解过程中，Lg-CN-7光催化剂中·OH的贡献率比Lg-CN光催化剂的4%提高到17%。 ·OH定量实验表明，Lg-CN-7光催化剂能够明显活化H2O生成·OH，且·OH的量是Lg-CN光催化剂的2.5倍。更重要的是，通过XPS、FT-IR和zeta电位测量到Lg-CN-7中存在大量末端-NH（14.6%）。通过在黑暗中添加H2O吸附实验来确认Lg-CN-7光催化剂的末端NH位点，这有利于吸附和活化H2O。结果表明，具有丰富边缘区域和末端-NH的Lg-CN-7光催化剂具有原位活化H2O生成·OH的特性。研究结果表明，设计和开发高效的 g-CN 光催化剂为激活原位自合成 H2O 和去除水中的莠去津开辟了新途径。