Abstract

In the last years, up to 90% of global energy demand for industrial and transportation sectors are supplied with fossil fuels, causing a high emission of greenhouse gases, including carbon dioxide and leading to a substantial depletion of carbon-based resources. A potential fuel for renewable energy is considered to be the hydrogen, besides to use of renewable energy based on solar, wind, geothermal and biomass. Up to now, CdS is the most important semiconductors with the 2.4 eV direct band gap that corresponds well with the maximum irradiation in the solar spectrum, and also has the advantage of a more negative conduction band edge compared to the H⁺/H₂ redox potential. In this paper, we reported the synthesis of Zn²⁺ doped CdS with polymorphic crystallization using hydrothermal method at low temperature, without organic precursor used for water splitting. The products were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy and UV-visible diffuse reflectance spectra. From Tauc plot the optical energy gap for undoped CdS was found to be nearly to 2.28 eV and increase to 2.44 eV for Cd_0.5Zn_0.5S. From photoluminescence spectroscopy measurements showthe two broad emission peaks located at ~535 and ~595 nm which is high for samples Cd_0.8Zn_0.2S and Cd_0.8Zn_0.5S compared with samples CdS, Cd_0.7Zn_0.3S and Cd_0.6Zn_0.4S. The PL peaks indicates defects, however, the increment in the photoluminescence spectroscopy intensity indicates the higher amount of defects. The higher amount of defects and vacancies present in samples Cd_0.8Zn_0.2S and Cd_0.8Zn_0.5S is beneficial for the H₂ production rates. The H₂ production after 12 h of Cd_1–xZn_xS samples is 204 (μmol for undoped CdS and increase to 277 μmol for Cd_0.6Zn_0.4S and 384 μmol for Cd_0.5Zn_0.5S respectively. The effect of PdS on the photocatalytic properties of Zn²⁺ doped CdS was investigated for hydrogen evolution under visible light from water containing Na₂S and Na₂SO₃ as sacrificial reagents. To our knowledge, the effect of PdS on the photoactivity of Zn²⁺ doped CdS with polymorphic crystallization has not been reported before.

中文翻译：

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PDS 负载对 CD1–xZNxS 型光催化剂的影响

摘要

过去几年，全球工业和交通运输部门能源需求的 90% 由化石燃料供应，导致包括二氧化碳在内的温室气体大量排放，并导致碳基资源大量枯竭。除了使用基于太阳能、风能、地热能和生物质能的可再生能源外，可再生能源的潜在燃料被认为是氢。迄今为止，CdS是最重要的半导体，其直接带隙为2.4 eV，与太阳光谱中的最大辐照很好地对应，并且与H ⁺ /H ₂氧化还原相比，还具有导带边缘更负的优势潜在的。在本文中，我们报道了 Zn ^{2+的合成。}采用低温水热法多晶型掺杂CdS，没有用于水分解的有机前驱体。通过X射线粉末衍射、扫描电子显微镜、透射电子显微镜和紫外-可见漫反射光谱对产物进行了表征。从 Tauc 图中，发现未掺杂 CdS 的光学能隙接近 2.28 eV，而 Cd _0.5 Zn _0.5 S 的光学能隙增加到 2.44 eV。从光致发光光谱测量结果显示，位于 ~535 和 ~595 nm 处的两个宽发射峰很高样品 Cd _0.8 Zn _0.2 S 和 Cd _0.8 Zn _0.5 S 与样品 CdS、Cd _0.7 Zn _0.3相比S 和 Cd _0.6 Zn _0.4 S。PL 峰表示缺陷，然而，光致发光光谱强度的增加表明缺陷量较高。样品 Cd _0.8 Zn _0.2 S 和 Cd _0.8 Zn _0.5 S 中存在的大量缺陷和空位有利于 H ₂产率。_{Cd 1– x} Zn _x S 样品12 小时后的 H _{2产量为 204（未掺杂 CdS 为 μmol，Cd 0.6} Zn _{0.4 S 为 277 μmol，Cd 0.5} Zn _0.5为 384 μmolS分别。研究了 PdS 对 Zn ^{2+掺杂 CdS 光催化性能的影响，研究了在含有 Na} ₂ S 和 Na ₂ SO ₃作为牺牲试剂的水中在可见光下析氢的情况。据我们所知，PdS 对具有多晶型结晶的 Zn ²⁺掺杂 CdS 的光活性的影响以前没有报道过。