Research Group of Environmental and Inorganic Photochemistry, Center for Natural Sciences, Faculty of Engineering, University of Pannonia, P.O. Box 1158, H-8210 Veszprém, Hungary.
Environmental Mineralogy Research Group, Research Institute of Biomolecular and Chemical Engineering, University of Pannonia, P.O. Box 1158, H-8210 Veszprem, Hungary.
Molecules. 2022 Jul 4;27(13):4296. doi: 10.3390/molecules27134296.
Hydrogen as an environmentally friendly fuel can be produced by photocatalytic procedures from aqueous systems, utilizing HS, an industrial side-product, by conversion and storage of renewable solar energy. Although composites of CdS and ZnS prepared by co-precipitation are very efficient in heterogeneous photocatalytic H generation, the optimal conditions for their synthesis and the effects of the various influencing factors are still not fully clarified. In this work, we investigated how the efficiency of Cd.Zn.S composites modified with Ni(II) was affected by the doping method, Ni-content, hydrothermal treatment, and presence of a complexing agent (ammonia) used in the preparation. The composition, optical, and structural properties of the photocatalysts prepared were determined by ICP, DRS, XRD, TEM, and STEM-EDS. Although hydrothermal treatment proved preferable for Ni-free composites, Ni-modification was more efficient for untreated composites precipitated from ammonia-containing media. The best efficiency (14.9% quantum yield at 380 nm irradiation, 109.8 mmol/g/h hydrogen evolution rate) achieved by surface modification with 0.1-0.3% Ni(II) was 15% and 20% better than those for hydrothermally treated catalyst and similarly prepared Pt-modified one, respectively. Structural characterization of the composites clearly confirmed that the Ni ions were not embedded into the CdS-ZnS crystal lattice but were enriched on the surface of particles of the original catalyst in the form of NiO or Ni(OH). This co-catalyst increased the efficiency by electron-trapping, but its too high amount caused an opposite effect by diminishing the excitable surface of the CdS-ZnS particles.
氢气作为一种环保燃料，可以通过光催化程序从水体系中产生，利用 H₂S，一种工业副产物，通过转化和储存可再生太阳能。虽然通过共沉淀制备的 CdS 和 ZnS 复合材料在非均相光催化 H₂ 生成中非常有效，但它们的最佳合成条件和各种影响因素的影响仍未完全阐明。在这项工作中，我们研究了 Ni(II)掺杂的 Cd.Zn.S 复合材料的效率如何受到掺杂方法、Ni 含量、水热处理以及在制备中使用的络合剂（氨）的影响。通过 ICP、DRS、XRD、TEM 和 STEM-EDS 确定了所制备的光催化剂的组成、光学和结构特性。尽管水热处理对无 Ni 复合材料更为有利，但未经处理的复合材料在含氨介质中沉淀时，Ni 修饰更为有效。通过用 0.1-0.3% Ni(II)进行表面修饰，获得了最佳效率（在 380nm 照射下为 14.9%量子产率，氢气产生速率为 109.8mmol/g/h），比水热处理催化剂和类似制备的 Pt 修饰催化剂分别提高了 15%和 20%。对复合材料的结构表征清楚地证实，Ni 离子并未嵌入 CdS-ZnS 晶格中，而是以 NiO 或 Ni(OH)的形式富集在原始催化剂颗粒的表面。这种助催化剂通过电子捕获提高了效率，但过多的 Ni 含量会通过减少 CdS-ZnS 颗粒的可激发表面产生相反的效果。
