自稳定p型Cu_(2)WS_(4)多面体催化剂高效光催化还原Cr(Ⅵ)的性能研究

Highly Efficient Reduction of Cr(Ⅵ) to Cr(Ⅲ) and Cr(0) on a Self-stable p-type Cu_(2)WS_(4) Polyhedron

Cr(Ⅵ)是环境中一种高危污染物,针对它的脱毒和去除一直是研究的重点。因此,本项工作通过在Cu网上原位生长具有规则多面体结构的p型Cu_(2)WS_(4)光催化剂,并应用于光催化还原Cr(Ⅵ)的性能研究。Cu网的高导电率和Cu_(2)WS_(4)向下弯曲的能带结构促进了光生空穴向Cu_(2)WS_(4)的内部迁移,而电子被转移到Cu_(2)WS_(4)表面,将Cr(Ⅵ)还原为Cr(Ⅲ),甚至Cr(0)。位于Cu_(2)WS_(4)晶格边缘上的S原子通过H-S键与HCrO_(4)^(−)结合,促进了Cr(Ⅵ)的吸附和还原。此外,Cu_(2)WS_(4)中Cu^(2+)/Cu+和W^(6+)/W^(4+)的氧化还原电对消耗了空穴和多余电子,保证了多面体Cu_(2)WS_(4)的自稳定性和可持续性。由于其优异的催化性能和自支撑特性,改性后的Cu_(2)WS_(4)/Cu网对Cr(Ⅵ)(30 mg/L)的去除效率从pH=5时的19.84%提高到pH=1时的98.85%,是一种可以在宽pH范围内处理废水中有害重金属的优异光催化材料。

Cr(Ⅵ)is a highly hazardous pollutant in the environment,its detoxication and removal are always a challenge.Herein,ptype Cu_(2)WS_(4) photocatalyst with a regularly polyhedral structure was in-situ grown on Cu mesh and applied in photocatalytic reduction of Cr(Ⅵ).Because of the downward band bending,together with the supreme conductivity of the Cu substrate,the flowing holes migrate toward the inner space of Cu_(2)WS_(4),and the electrons are forced to the Cu_(2)WS_(4) surface for reducing Cr(Ⅵ)to Cr(Ⅲ)and even Cr(0).S atoms set on Cu_(2)WS_(4) lattice edges combine HCrO_(4)^(-)through an H-S bond with high affinity,enabling the efficient reduction of Cr(Ⅵ).Additionally,the redox pairs of Cu^(2+)/Cu^(+),W^(6+)/W^(4+) in Cu_(2)WS_(4) consume the holes and excess electrons,realizing the self-stability and sustainability of the polyhedral Cu_(2)WS_(4).On account of the outstanding catalytic performance and self-supported feature,the removal efficiency of Cr(Ⅵ)(30 mg/l)endowed by the resulting Cu_(2)WS_(4)/Cu mesh is increased from 19.84%at pH 5 to 98.85%at pH 1,which presents a workable approach to treating hazardous heavy metals from wastewater in a wide pH window.