Abstract Cobalt sulfide powders (CoS, Co9S8 and CoS1.97) were synthesized by solution combustion method using conventional and microwave heating routes. The powders were obtained using cobalt nitrate as both cobalt source and oxidizer together with proper amounts of thiourea as sulfidizing agent and glycine as an auxiliary reductant. Effects of thiourea and glycine amounts in conjunction with the type of combustion route, on the phase constituents, microstructure and optical properties were studied using infrared spectroscopy, thermal analysis, X-ray diffractometry, electron microscopy and diffuse reflectance spectrometry techniques. The results revealed that single phase cobalt sulfides can be delivered by precise adjustment of thiourea and glycine amounts and a proper heating (conventional or microwave) rout. Co9S8 single phase was obtained using equal amounts of thiourea and glycine by both microwave and conventional heating modes. Using thiourea/glycine ratio of 1.5, leads to the formation of CoS1.97 single phase by conventional heating, while CoS was obtained when microwave heating was applied. Increasing the amount of thiourea caused particle size increment. Maximum photocatalytic degradation efficiency (89 and 89.5%) of methylene blue was obtained at pH = 9 for microwave combusted samples. Quenching tests in the presence of •OH− radical scavenger (isopropyl alcohol) showed that the major oxidizing species were • OH− radicals.

中文翻译：

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混合燃料溶液燃烧合成硫化钴的光催化性能

摘要 硫化钴粉体（CoS、Co9S8 和 CoS1.97）采用常规和微波加热途径通过溶液燃烧法合成。以硝酸钴为钴源和氧化剂，加入适量硫脲为硫化剂，甘氨酸为辅助还原剂，制得粉末。使用红外光谱、热分析、X 射线衍射、电子显微镜和漫反射光谱技术研究了硫脲和甘氨酸用量与燃烧路线类型、相成分、微观结构和光学性质的影响。结果表明，单相硫化钴可以通过硫脲和甘氨酸量的精确调整和适当的加热（常规或微波）路线来交付。Co9S8 单相是使用等量的硫脲和甘氨酸通过微波和常规加热模式获得的。使用 1.5 的硫脲 / 甘氨酸比率，通过常规加热导致形成 CoS1.97 单相，而在应用微波加热时获得 CoS。增加硫脲的量导致粒度增加。对于微波燃烧样品，在 pH = 9 时获得了亚甲蓝的最大光催化降解效率（89% 和 89.5%）。• OH- 自由基清除剂（异丙醇）存在下的淬火试验表明，主要的氧化物质是 • OH- 自由基。而当应用微波加热时获得 CoS。增加硫脲的量导致粒度增加。对于微波燃烧样品，在 pH = 9 时获得了亚甲蓝的最大光催化降解效率（89% 和 89.5%）。• OH- 自由基清除剂（异丙醇）存在下的淬火试验表明，主要的氧化物质是 • OH- 自由基。而当应用微波加热时获得 CoS。增加硫脲的量导致粒度增加。对于微波燃烧样品，在 pH = 9 时获得了亚甲蓝的最大光催化降解效率（89% 和 89.5%）。在•OH- 自由基清除剂（异丙醇）存在下的淬火试验表明，主要的氧化物质是• OH- 自由基。