The interfacial structure of InP(100) in contact with HCl and H2SO4 studied by reflection anisotropy spectroscopy

Indium phosphide and derived compound semiconductors are materials often involved in high-efficiency solar water splitting due to their versatile opto-electronic properties. Surface corrosion, however, typically deteriorates the performance of photoelectrochemical solar cells based on this material class. It has been reported that (photo)electrochemical surface functionalisation protects the surface by combining etching and controlled corrosion. Nevertheless, the overall involved process is not fully understood. Therefore, access to the electrochemical interface structure under operando conditions is crucial for a more detailed understanding. One approach for gaining structural insight is the use of operando reflection anisotropy spectroscopy. This technique allows the time-resolved investigation of the interfacial structure while applying potentials in the electrolyte. In this study, p-doped InP(100) surfaces are cycled between anodic and cathodic potentials in two different electrolytes, hydrochloric acid and sulphuric acid. For low, 10 mM electrolyte concentrations, we observe a reversible processes related to the reduction of a surface oxide phase in the cathodic potential range which is reformed near open-circuit potentials. Higher concentrations of 0.5 N, however, already lead to initial surface corrosion.Comment: 10 pages, 6 figure

Dataset for publication "In Situ Monitoring of the Al(110)-[EMImCl]:AlCl3 Interface by Reflection Anisotropy Spectroscopy"

<p>Dataset are obtained from Reflection anisotropy spectroscopy, CV, SEM/EDX, and computaitonal RAS</p><p>The data are sorted according to the Figures of the paper.</p><p>Abstract of the paper:</p><p>Recently, Al-batteries (AlBs) have become promising candidates for post-lithium batteries, with [EMImCl]:AlCl3 (1:1.5) as the most commonly used electrolyte. However, progress in the development of AlBs is currently hindered by the lack of understanding of its solid-electrolyte interface. Monitoring the structure of this interface under operational conditions by complementary spectroscopy could help to identify and overcome bottlenecks of the system. Reflection anisotropy spectroscopy (RAS), an optical in situ technique, provides access to physical and chemical properties of electrochemical interfaces on an atomistic level. Herein, we report the first example of RAS as an in situ characterization technique for non-aqueous battery systems, investigating an Al(110)-based model system. During chemical pre-treatment in [EMImCl]:AlCl3 , the Al(110) surface passivation film is modified. The oxide film is partially etched while an inhomogeneous passivation layer forms, increasing the surface roughness. Upon electrochemical cycling, applied potential-dependent oscillations of the anisotropy are observed and demonstrate the applicability of RAS to monitor phenomena such as plating/stripping and surface passivation in real-time.</p&gt