Potential-sensing electrochemical atomic force microscopy for in operando analysis of water-splitting catalysts and interfaces
Potential-sensing electrochemical atomic force microscopy for in operando analysis of water-splitting catalysts and interfaces
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DOI：
10.1038/s41560-017-0048-1
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发表时间：
2018-01-01
期刊：
影响因子：
56.7
通讯作者：
Boettcher, Shannon W.
中科院分区：
文献类型：
--
作者：
Nellist, Michael R.;Laskowski, Forrest A. L.;Boettcher, Shannon W.
非均相电化学现象，例如使用半导体和/或电催化剂进行（光）电化学水分解以产生氢气，是由累积的电荷载流子驱动的，从而促进电荷转移的界面电化学势梯度。然而，使用测量/控制导电电极基底的电势的常规电化学技术通常不可能测量操作期间的“表面”电化学电势。在这里，我们证明原子力显微镜悬臂的纳米级导电尖端可以感知操作中电催化剂的表面电化学势。为了证明实用性，我们测量了氢氧化磷酸钴 (CoPi) 的电势依赖性和厚度依赖性电子特性。然后我们证明，当 CoPi 沉积在发光赤铁矿 (α-Fe2O3) 光电极上时，它既可以充当空穴收集器，也可以充当析氧催化剂。我们通过比较 CoPi 修饰的平面和介孔赤铁矿的表面电势来证明该技术的多功能性，并讨论了在电化学现象研究中更广泛应用的可行性。
Heterogeneous electrochemical phenomena, such as (photo) electrochemical water splitting to generate hydrogen using semiconductors and/or electrocatalysts, are driven by the accumulated charge carriers and thus the interfacial electrochemical potential gradients that promote charge transfer. However, measurements of the "surface" electrochemical potential during operation are not generally possible using conventional electrochemical techniques, which measure/control the potential of a conducting electrode substrate. Here we show that the nanoscale conducting tip of an atomic force microscope cantilever can sense the surface electrochemical potential of electrocatalysts in operando. To demonstrate utility, we measure the potential-dependent and thickness-dependent electronic properties of cobalt (oxy) hydroxide phosphate (CoPi). We then show that CoPi, when deposited on illuminated haematite (alpha-Fe2O3) photoelectrodes, acts as both a hole collector and an oxygen evolution catalyst. We demonstrate the versatility of the technique by comparing surface potentials of CoPi-decorated planar and mesoporous haematite and discuss viability for broader application in the study of electrochemical phenomena.