Adaptive semiconductor/electrocatalyst junctions in water-splitting photoanodes
Adaptive semiconductor/electrocatalyst junctions in water-splitting photoanodes
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DOI：
10.1038/nmat3811
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发表时间：
2014-01-01
期刊：
影响因子：
41.2
通讯作者：
Boettcher, Shannon W.
中科院分区：
文献类型：
--
作者：
Lin, Fuding;Boettcher, Shannon W.
高效的光电化学水分解装置需要电催化剂（ECs）和光吸收半导体（SCs）的集成，但SC / EC界面的能量学和电荷转移过程尚不清楚。我们制作了模型EC涂层的单晶TiO2电极，并使用两个工作电极在原位直接探测SC / EC界面，以独立监测和控制SC和EC的电位和电流。我们发现，氧化还原活性离子渗透性EC如Ni(OH)(2)或NiOOH产生“自适应”SC / EC结，其中有效肖特基势垒高度随EC的氧化水平原位变化。相比之下，致密的、离子不渗透的IrOx ECs产生恒定势垒高度的“埋藏”结。在TiO2上热沉积的致密NiOx转化为离子渗透的Ni(OH) 2或NiOOH与增加的视光电压和填充因子相关。这些结果为SC/EC界面的动态行为提供了新的见解，以指导高效SC/EC设备的设计。它们还展示了一类新的自适应半导体结。
High-efficiency photoelectrochemical water-splitting devices require the integration of electrocatalysts (ECs) with light-absorbing semiconductors (SCs), but the energetics and charge-transfer processes at SC / EC interfaces are poorly understood. We fabricate model EC-coated single-crystal TiO2 electrodes and directly probe SC / EC interfaces in situ using two working electrodes to independently monitor and control the potential and current at both the SC and the EC. We discover that redox-active ion-permeable ECs such as Ni(OH)(2) or NiOOH yield 'adaptive' SC / EC junctions where the effective Schottky barrier height changes in situ with the oxidation level of the EC. In contrast, dense, ion-impermeable IrOx ECs yield constant-barrier-height 'buried' junctions. Conversion of dense, thermally deposited NiOx on TiO2 into ion-permeable Ni(OH) 2 or NiOOH correlated with increased apparent photovoltage and fill factor. These results provide new insight into the dynamic behaviour of SC / EC interfaces to guide the design of efficient SC/EC devices. They also illustrate a new class of adaptive semiconductor junctions.