Dual-Sensitizer Photoanode for Bromide Oxidation
Dual-Sensitizer Photoanode for Bromide Oxidation
复制标题
用于溴化物氧化的双敏化剂光电阳极
DOI：
10.1021/acsaem.0c02544
复制
发表时间：
2021
影响因子：
6.4
通讯作者：
Meyer, Gerald J.
中科院分区：
文献类型：
--
作者：
Turlington, Michael D.;Brady, Matthew D.;Meyer, Gerald J.
研究了一种双增敏介孔薄膜光阳极在pH 5.6水溶液中对溴化物进行可见光氧化的特性。薄膜由相互连接的纳米颗粒组成，其中金红石型sno2核，(1-氰基-2-（4-（二对叔胺苯基）乙烯基）膦酸（Org）对可见光敏化的tio2壳层，以及以[Ru(bpz)2(4,4 ' -(PO3H2)2-2,2-联吡啶]2+(Ru)为锚定的al2o3覆盖层，其中bpz为2,2 ' -联吡嗪。本文将这种材料称为CS|Org|Al2O3| ru1，它由两种空间上分离的敏化剂组成：Org是一种强效光还原剂，有助于将定量激发态电子注入纳米粒子（ϕ = 1），而ru2可以再生orgox并催化溴化物氧化。该产物与溴化物反应，反应速率常数为2 × 107M-1s-1。在运行的HBr分裂电池中，双敏化剂光阳极的光电流可达200 μA/cm2，明显优于单独使用org （40 μA/cm2）或ru （2 μA/cm2）的光阳极。尽管通过瞬态吸收光谱确定了非生产性还原猝灭途径（Org+Ru*→Orgox+Rured），但仍实现了光电流增强。发现两种敏化剂之间的绝缘al2o3层的厚度会影响还原淬火途径的收率。用蒙特卡罗模拟进行的时间分辨各向异性测量为穿过绝缘氧化物表面的横向分子间Ru*+ Ru↔Ru + Ru*能量传递提供了速率常数，这一行为有望提高与orgoxin CS|Org|Al2O3|Ru相遇的概率。这些数据表明，双敏化剂光阳极方法可以用于利用催化更有利的条件进行介导的水氧化。
A dual-sensitizer mesoporous thin-film photoanode has been characterized for visible light-driven bromide oxidation in an aqueous pH 5.6 solution. The thin film is composed of interconnected nanoparticles with a rutile SnO2core, a TiO2shell sensitized to visible light with (1-cyano-2-(4-(di-p-tolylamino)phenyl)vinyl)phosphonic acid (Org), and an Al2O3overlayer to which [Ru(bpz)2(4,4′-(PO3H2)2-2,2-bipyridine]2+(Ru) was anchored, where bpz is 2,2′-bipyrazine. This material herein referred to as CS|Org|Al2O3|Ruis composed of two spatially isolated sensitizers:Org, a potent photoreductant that facilitates quantitative excited-state electron injection into the core/shell nanoparticle (ϕ = 1), andRuthat regeneratesOrgoxand catalyzes bromide oxidation. TheRuoxproduct was found to react with bromide with a rate constantkreg= 2 × 107M–1s–1. In an operational HBr splitting cell, the dual-sensitizer photoanode sustained 200 μA/cm2of photocurrent, significantly outperforming photoanodes with eitherOrg(40 μA/cm2) orRu(2 μA/cm2) alone. The photocurrent enhancement was achieved in spite of a nonproductive reductive quenching pathway (Org+Ru*→Orgox+Rured) that was identified through transient absorption spectroscopy. The thickness of the insulating Al2O3layer between the two sensitizers was found to impact the yield of the reductive quenching pathway. Time-resolved anisotropy measurements with Monte Carlo simulations provided the rate constant for the lateral intermolecularRu*+ Ru↔Ru + Ru* energy transfer across an insulating oxide surface, a behavior expected to enhance the probability of encounters withOrgoxin CS|Org|Al2O3|Ru. The data indicate that a dual-sensitizer photoanode approach could be utilized for a mediated water oxidation that exploits conditions where catalysis is more favorable.