Kurnosenko Sergei A, Silyukov Oleg I, Rodionov Ivan A, Baeva Anna S, Burov Andrei A, Kulagina Alina V, Novikov Silvestr S, Zvereva Irina A
Department of Chemical Thermodynamics and Kinetics, Institute of Chemistry, Saint Petersburg State University, 199034 Saint Petersburg, Russia.
Molecules. 2024 May 2;29(9):2108. doi: 10.3390/molecules29092108.
The layered double hydroxides (LDHs) of transition metals are of great interest as building blocks for the creation of composite photocatalytic materials for hydrogen production, environmental remediation and other applications. However, the synthesis of most LDHs is reported only by the conventional coprecipitation method, which makes it difficult to control the catalyst's crystallinity. In the present study, ZnCr- and NiCr-LDHs have been successfully prepared using a facile hydrothermal approach. Varying the hydrothermal synthesis conditions allowed us to obtain target products with a controllable crystallite size in the range of 2-26 nm and a specific surface area of 45-83 m∙g. The LDHs synthesized were investigated as photocatalysts of hydrogen generation from aqueous methanol. It was revealed that the photocatalytic activity of ZnCr-LDH samples grows monotonically with the increase in their average crystallite size, while that of NiCr-LDH ones reaches a maximum with intermediate-sized crystallites and then decreases due to the specific surface area reduction. The concentration dependence of the hydrogen evolution activity is generally consistent with the standard Langmuir-Hinshelwood model for heterogeneous catalysis. At a methanol content of 50 mol. %, the rate of hydrogen generation over ZnCr- and NiCr-LDHs reaches 88 and 41 μmol∙h∙g, respectively. The hydrothermally synthesized LDHs with enhanced crystallinity may be of interest for further fabrication of their nanosheets being promising components of new composite photocatalysts.
过渡金属层状双氢氧化物（LDHs）作为用于制氢、环境修复及其他应用的复合光催化材料的构建单元，备受关注。然而，大多数LDHs的合成仅通过传统共沉淀法报道，这使得难以控制催化剂的结晶度。在本研究中，采用简便的水热法成功制备了ZnCr-LDHs和NiCr-LDHs。改变水热合成条件使我们能够获得微晶尺寸在2-26nm范围内可控且比表面积为45-83m∙g的目标产物。对合成的LDHs作为从甲醇水溶液中制氢的光催化剂进行了研究。结果表明，ZnCr-LDH样品的光催化活性随其平均微晶尺寸的增加而单调增长，而NiCr-LDH样品的光催化活性在微晶尺寸为中等大小时达到最大值，然后由于比表面积减小而降低。析氢活性的浓度依赖性总体上与多相催化的标准朗缪尔-欣谢尔伍德模型一致。在甲醇含量为50mol.%时，ZnCr-LDHs和NiCr-LDHs上的产氢速率分别达到88和41μmol∙h∙g。具有增强结晶度的水热合成LDHs对于进一步制备其纳米片可能具有吸引力，这些纳米片是新型复合光催化剂的有前景的组分。
