摘要
采用高温固相法合成了可见光响应的Cu和W共掺杂NaTaO3光催化剂NaTaO3∶Cu/W,研究了Cu与W的摩尔比和共掺杂量(摩尔分数)对NaTaO3∶Cu/W晶体结构、形貌、光吸收性质和可见光催化分解甲醇水溶液制氢活性的影响规律.结果表明,Cu,W分别以Cu(Ⅱ)和W(Ⅵ)存在于NaTaO3∶Cu/W中;Cu,W共掺杂不改变NaTaO3的晶体结构,但能引起晶格畸变,减小表面台阶间距;当固定Cu与W的摩尔比,增大共掺杂量时,进入NaTaO3晶格的掺杂离子逐渐增多,使(020)晶面的衍射峰逐渐向高角度方向移动,光吸收边红移;进一步增大共掺杂量,(020)晶面衍射峰则向低角度方向移动.说明过量的掺杂离子不能有效进入晶格,Cu,W对NaTaO3的掺杂存在最大值;当Cu与W的摩尔比为1∶2,1∶3和1∶4时,最大共掺杂量分别为8%,6%和4%;NaTaO3∶Cu/W在最大共掺杂量时光催化制氢活性明显提高.其中,NaTaO3∶Cu/W的光催化制氢活性在Cu与W的摩尔比为1∶4,共掺杂量为4%时达到最佳值.结果表明,Cu,W共掺杂Na-TaO3可在一定程度上实现电荷平衡,降低光生电子和空穴的复合几率,从而提高光催化活性.
Copper and tungsten codoped NaTaO3（NaTaO3： Cu/W） photocatalysts were prepared by a high-temperature solid state synthetic method. The effects of the molar ratio of Cu to W and the total doping amount on the phase structure, morphology, optical absorption properties as well as photocatalytic activities for hydrogen production from methanol aqueous solutions under visible light were studied. The results show that the metallic dopants exist in forms of Cu（Ⅱ） and W（Ⅵ） in NaTaO3：Cu/W, respectively. The codoping of Cu and W into NaTaO3 does not affect the crystal structure, but distorts the crystal lattice and decreases the characte-ristic steps on the surface. With increasing the total doping amount at a constant Cu/W molar ratio, the increased doping ions make the （020） diffraction peak gradually shift to higher angles as well as the red shift of the absorption edge to the visible light range. However, further increase of total doping amount results in the shift of the （020） diffraction peak to lower angle. This indicates that excessive metallic ions can not be doped into the lattice effectively. There is a maximum doping amount for the codoping of Cu, W into NaTaO3. When the molar ratios of Cu to W are 1： 2, 1： 3 and 1： 4, the maximum total doping amount are 8%, 6% and 4%, respectively. NaTaO3： Cu/W exhibits the enhanced photocatalytic activity for hydrogen evolution at the maximum total doping amount and obtains the highest activity when the molar ratios of Cu to W is 1： 4, the total doping amount is 4%. It indicates that the codoping of Cu and W ions into NaTaO3 at an appropriate Cu/W molar ratio can maintain the charge balance to a great extent, suppress the formation of oxygen defects in the lattice and inhibit the recombination of photogenerated electrons and holes so that the photocatalytic activity for hydrogen production is improved.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
2012年第11期2537-2543,共7页
Chemical Journal of Chinese Universities
基金
国家自然科学基金(批准号:51002111
21001086)
中国博士后科学基金(批准号:20100471163
201104494)
湖北省自然科学基金(批准号:2010CDA030)
武汉市学科带头计划项目(批准号:201150530145)
中央高校基本科研业务费专项资金(批准号:2012-IV-085)资助
关键词
高温固相法
钽酸钠
共掺杂
光催化产氢
High-temperature solid state synthetic method
NaTaO3
Codoping
Photocatalytic hydrogen evolution
