Ni-CH3CH2NH2/H1.78Sr0.78Bi0.22Nb2O7复合层状钙钛矿的合成及光催化分解水产氢性能

摘要

自从分解水产氢被首次报道以来,许多光催化剂被开发出来并用于光催化分解水产氢.然而,由于光生电子和空穴的复合率普遍较高,大部分的光催化剂分解水产氢效率都很低.因此,开发新型高效的光催化材料至关重要.具有(Bi2O2)2+(Am-1MmO3m+1)2?通式的Aurivillius相层状钙钛矿材料因具有独特的层状结构、元素可调性以及优异的电荷传输和分离能力而广泛应用于光催化分解水和去除有机污染物.此外,当该类层状钙钛矿被剥离成超薄纳米片时,其光催化性能进一步提高.为了进一步提高层状钙钛矿的载流子分离能力,将客体(如贵金属,半导体等)通过化学反应的途径插入到层状钙钛矿的层间区域,从而合成出复合层状钙钛矿被广泛发展和应用.然而,引入的客体主要是贵金属和半导体,这类客体的高成本和不均匀分布制约了其进一步的应用.由于廉价、无毒和稳定等优点,镍基材料如Ni,NiO,Ni2O3,NiS,NiS2,Ni(OH)2和Ni(OH)x等被广泛用作增强电极材料的光电性能和催化剂的光催化分解水产氢性能的助催化剂.本文采用简单的原位化学反应法制备出镍基配合物Ni-CH3CH2NH2(Ni-EA)插层的Ni-CH3CH2NH2/H1.78Sr0.78Bi0.22Nb2O7(Ni-EA/HSN Ns)复合层状钙钛矿;然后采用X-射线衍射(XRD)、傅立叶变换红外光谱(FTIR)、X-射线光电子能谱(XPS)、紫外-可见漫反射光谱等手段对Ni-EA/HSN Ns光催化剂进行了系统的研究.XRD结果表明,引入Ni2+后,HSN Ns层间距减小并且平行于钙钛矿层的晶面结晶度增强,证明HSN Ns沿垂直于钙钛矿层的方向出现了层层组装.FTIR和XPS结果表明,引入的Ni2+与HSN Ns层间和表面的乙胺分子之间存在较强的相互作用,结合高分辨透射电镜图可知,Ni的存在形态可能为配合物Ni-EA.由此可见,当向HSN Ns中引入Ni2+时,Ni2+和HSN Ns层间和表面的乙胺分子反应生成带正电的配合物Ni-EA,由于Ni-EA与HSN Ns的钙钛矿层带有异种电荷,两者之间存在较强的静电相互作用力,从而引起钙钛矿纳米片HSN Ns的层层组装,最后形成Ni-EA/HSN Ns复合层状钙钛矿.光催化分解水产氢性能测试结果表明,当引入0.5 wt%Ni时,复合层状钙钛矿表现出最优的光催化性能.与HSN Ns(241.58μmol/h)相比,0.5%Ni-EA/HSN Ns的光催化分解水产氢速率(372.67μmol/h)提高了0.54倍,表现出与0.5%Pt/HSN Ns可比拟的光催化活性,可见,非贵金属Ni具有替代贵金属Pt的能力.进一步的研究表明,镍基配合物Ni-EA显著增强了催化剂的光生载流子的传输和分离能力,从而提高了其光催化分解水产氢性能.该文为光催化分解水产氢提供了一种简便的合成非贵金属配合物助催化剂的方法.%The nickel-based complex Ni-CH3CH2NH2-intercalated niobate layered perovskite Ni-CH3CH2NH2/H1.78Sr0.78Bi0.22Nb2O7 was synthesized via a facile in situ chemical reaction method. Using ultrathin H1.78Sr0.78Bi0.22Nb2O7 nanosheets and nickel acetate as precursors. The composition, structure, photophysical properties, and photocatalytic activity for H2 production of Ni-CH3CH2NH2/H1.78Sr0.78Bi0.22Nb2O7 were studied systematically. The photocatalyst loaded with 0.5 wt% Ni exhibited the highest H2 evolution rate of 372.67 μmo/h. This was 0.54 times higher than the activity of the H1.78Sr0.78Bi0.22Nb2O7 nanosheets. The activity of the optimized Ni-CH3CH2NH2/H1.78Sr0.78Bi0.22Nb2O7 was comparable to that of the Pt-loaded sample under the same reaction conditions. The photocatalytic activity of the Ni-CH3CH2NH2/H1.78Sr0.78Bi0.22Nb2O7 was mainly attributed to the excellent separation of photogenerated carriers, after formation of the intercalated complex Ni-CH3CH2NH2. This study provides a facile strategy to synthesize a non-precious metal-loaded photocatalyst for H2 production.