Boosting visible-light-driven water splitting over LaTaON_(2) via Al doping

通过Al掺杂促进可见光驱动的LaTaON_(2)分解水

LaTaON_(2)is an attractive visible-light-active photocatalyst for water splitting due to its broad visible light absorption as far as 650 nm and proper band edge positions.Notwithstanding these promising properties,LaTaON_(2)generally exhibits poor photocatalytic activity because of its high defect concentration that severely hinders charge separation.Here,LaTaON_(2)has been modified by doping Al into the Ta sublattice,i.e.,LaTa_(1−x)Al_(x)O_(1+y)N_(2−y)(0≤x≤0.20).Al doping not only inhibits the defect concentration and increases surface hydrophilicity but also maintains the desired visible light absorption of LaTaON_(2).These important modifications substantially ameliorate the charge separation conditions within LaTaON_(2)and are responsible for a much enhanced photocatalytic performance for water redox reactions under visible light illumination.Under optimal conditions,the Al-doped LaTaON_(2)delivers an apparent quantum efficiency of 1.17%at 420±20 nm for water oxidation into O_(2),outperforming most LaTaON_(2)-based photocatalysts.These findings highlight Al as a useful dopant to open up the photocatalytic potential of metal oxynitrides whose activity is often undermined by a high defect concentration.

LaTaON_(2)是一种极具吸引力的可见光活性光催化水分解材料.它的吸收波长能够达到650 nm,并且符合水分解反应的热力学要求,是光催化水分解的候选材料.尽管LaTaON_(2)具有这些优异的性质,它的光催化活性通常不够理想.这是由于LaTaON_(2)材料通常具有较高的缺陷浓度,严重阻碍了电荷分离.在本文中,我们通过将Al掺杂到Ta亚晶格中来对LaTaON_(2)材料进行改性,得到LaTa_(1−x)Al_(x)O_(1+y)N_(2−y)(0≤x≤0.20).Al掺杂不仅抑制了LaTaON_(2)材料中的缺陷浓度,增加了其表面亲水性,而且还保持了材料原有的可见光吸收性质.这些改进显著改善了La-TaON_(2)材料内的电荷分离情况,并极大增强了材料可见光下的光催化氧化水制氧性能.在最佳条件下,Al掺杂的LaTaON_(2)在420±20 nm处水氧化的表观量子效率达到1.17%,这个性能要优于大多数已报道的LaTaON_(2)光催化剂.这些发现验证了Al作为掺杂剂的优越性,也为进一步改性其他金属氧氮化物光催化剂的活性提供了新思路.