高比表面积g-C_3N_4负载Keggin型Cu单晶取代杂多酸特异性光催化还原CO_2制CH_4

以三聚氰胺、二水合钨酸钠、二水合磷酸氢二钠、CuCl_2等为原料,采用乙醚萃取法和模板剂法分别制备了Keggin型Cu单晶取代的杂多酸(PW₁₁Cu)和高比表面积g-C_3N_4(PCN),通过浸渍法将PW₁₁Cu负载于PCN上制得催化剂,对制得的催化剂进行了FTIR、XRD、N_2吸附-脱附、UV-Vis漫反射光谱、EIS光谱、荧光光谱表征,通过光催化还原CO_2对催化剂的活性及稳定性进行了考察,并对催化机理进行了探究。表征结果显示,比表面积的增加及PW₁₁Cu的负载均能有效降低光生电子-空穴的复合几率,拓宽光响应范围。实验结果表明,Cu单晶取代杂多酸的负载能够特异性还原CO_2为CH_4,当PW₁₁Cu负载量为15%(w)时表现出最佳的催化活性,且循环使用5次后催化剂的活性没有明显变化。

High surface area g-C_3N_4 loaded Keggin type Cu mono-substituted heteropoly acid toward specific photocatalytic reduction of CO_2 to CH_4

Using melamine,Na2WO4·2H2O,Na2HPO4·2H2O and CuCl2 as precursors,Keggin type Cu substituted heteropoly acid potassium(PW11Cu)and high surface area g-C3N4(PCN)were synthesized by extraction method with ether and template method,respectively.PW11Cu was loaded on PCN by dipping method.The structure of catalysts was characterized by FTIR,XRD,BET,UVVis spectroscopy,EIS spectroscopy and photoluminescence spectrum.The activity and stability of catalysts were tested toward reduction CO2,and the mechanism of catalysis was also explored.The results indicated that the increase of the surface area and the loaded of PW11Cu could effectively reduce the recombination of the photogenerated electrons and holes,and broaden the range of light response.The result showed that the loading of the PW11Cu could specifically reduce CO2 to CH4.The catalyst exhibited the highest photocatalytic activity when the doping amount of PW11Cu was 15%(w)and the activity did not change significantly after 5 cycles.