Ag/ZnO复合材料在氮气光固定中的应用:构造肖特基势垒以实现有效的电荷载流子分离

Application of Ag/ZnO composite materials in nitrogen photofixation:Constructing Schottky barrier to realized effective charge carrier separation

将氮气(N_(2))光催化还原为氨(NH_(3))是一种可持续的能源生产方法。等离激元共振光催化剂能够通过表面等离激元共振效应实现太阳能的有效转化,也因此受到越来越广泛的关注。然而,热载流子往往会在催化固氮的过程中发生重新结合。本研究将具有等离激元共振效应的Ag纳米粒子与ZnO半导体复合(Ag/ZnO)并应用于氮气光固定。与ZnO相比,Ag/ZnO在氮气光固定的催化活性得到了提高,室温下氨生成速率达到120μmol·g_(cat.)^(-1)·h^(-1)。进一步的机理研究表明在Ag纳米颗粒与ZnO的界面处形成了肖特基势垒,这大幅度促进了光生电子-空穴对的分离。Ag纳米粒子通过表面等离激元共振效应生成热载流子,所形成的肖特基势垒则促进了电子从Ag向ZnO转移。此外,ZnO中的富电子Zn^(+)可能作为活性位点以吸附和活化氮气分子,从而促进氮气光固定的进行。

The photocatalytic reduction of nitrogen(N_(2))to ammonia(NH_(3))is a sustainable energy product method.Plasmonic photocatalysts can achieve effective conversion of solar energy via surface plasmon resonance(SPR),and therefore have attracted more and more attention.However,the photo-induced hot charge-carriers tend to recombine during N_(2) reduction process.Ag nanoparticles with plasmon resonance effect with ZnO semiconductor(Ag/ZnO)and apply them to N_(2) photofixation were studied.Compared with pure ZnO,Ag/ZnO exhibited enhanced catalytic activity in N_(2) photofixation,and the NH_(3) production rate at room temperature can reach 120μmol·g_(cat.)^(-1)·h^(-1).Mechanism studies revealed that a Schottky barrier was formed at the interface between Ag nanoparticles and ZnO,which boosted the separation of photo-induced electron-hole pairs.Ag nanoparticles generated hot charge carriers via SPR effect,and the formed Schottky barrier facilitated the transfer of electrons from Ag to ZnO.The electron-rich Zn^(+)species in ZnO was speculated to serve as active sites to adsorb and activate N_(2) molecules,thereby promoting N_(2) photofixation.