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Enhanced photocatalytic H2 evolution on ultrathin Cd0.5Zn0.5S nanosheets without a hole scavenger: Combined analysis of surface reaction kinetics and energy-level alignment
Chemical Engineering Journal ( IF 13.3 ) Pub Date : 2021-09-24 , DOI: 10.1016/j.cej.2021.132608
Wenhua Xue 1 , Xue Bai 1 , Jingzhuo Tian 1 , Xinyi Ma 1 , Xiaoyun Hu 2 , Jun Fan 1 , Enzhou Liu 1
Affiliation  

The surface photocatalytic water splitting kinetics of ultrathin CdZnS nanosheets without hole scavengers is critically examined, focusing on the effects of the pH and NaOH as an electrolyte. In aqueous NaOH, hole scavenging from CdZnS is enhanced, which reduces catalyst photocorrosion. Based on the Langmuir-Hinshelwood model, OH adsorption on CdZnS is the rate-limiting step of the whole process, and the reaction rate increases with increase in pH and temperature. The hydrogen evolution reaction (HER) activity of CdZnS reaches 12.44 and ∼ 20 mmol‧g‧h at 303.15 K and 313.15 K (6 M NaOH, 0.5 h), respectively, two orders of magnitude higher than that in pure water. At high pH, direct OH oxidation is favored, enhancing water splitting and indicating that water oxidation shifts to a ∙OH production pathway with activation energy approximately of 23.73 kJ‧ mol. Promisingly, this strategy to improve H production rates is applicable to other chalcogenide photocatalysts (CdS, CdMnS, ZnSe and CdZnSe).

中文翻译:

无空穴清除剂的超薄 Cd0.5Zn0.5S 纳米片上增强光催化产氢:表面反应动力学和能级排列的组合分析

对不含空穴清除剂的超薄 CdZnS 纳米片的表面光催化水分解动力学进行了严格的研究,重点关注 pH 值和 NaOH 作为电解质的影响。在 NaOH 水溶液中,CdZnS 的空穴清除作用增强,从而减少了催化剂的光腐蚀。根据Langmuir-Hinshelwood模型,OH在CdZnS上的吸附是整个过程的限速步骤,反应速率随着pH和温度的升高而增加。 CdZnS的析氢反应(HER)活性在303.15 K和313.15 K(6 M NaOH,0.5 h)下分别达到12.44和∼20 mmol·g·h,比纯水中的析氢反应活性高两个数量级。在高 pH 值下,有利于直接 OH 氧化,增强水分解,表明水氧化转向 ∙OH 生成途径,活化能约为 23.73 kJ‧ mol。这种提高 H 产率的策略有望适用于其他硫属化物光催化剂(CdS、CdMnS、ZnSe 和 CdZnSe)。
更新日期:2021-09-24
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