Nanophase Evolution at Semiconductor/Electrolyte Interface in Situ Probed by Time-Resolved High-Energy Synchrotron X-ray Diffraction

Abstract

Real-time evolution of nanoparticles grown at the semiconductor/electrolyte interface formed between a single crystalline n-type GaAs wafer and an aqueous solution of AgNO(3) has been studied by using high-energy synchrotron X-ray diffraction. The results reveal the distinct nucleation and growth steps involved in the growth of anisotropic Ag nanoplates on the surface of the GaAs wafer. For the first time, a quick transit stage is observed to be responsible for the structural transformation of the nuclei to form structurally stable seeds that are critical for guiding their anisotropic growth into nanoplates. Reaction between a GaAs wafer and AgNO(3) solution at room temperature primarily produces Ag nanoplates on the surface of the GaAs wafer in the dark and at room temperature. In contrast, X-ray irradiation can induce charge separation in the GaAs wafer to drive the growth of nanoparticles made of silver oxy salt (Ag(7)NO(11)) and silver arsenate (Ag(3)AsO(4)) at the semiconductor/electrolyte interface if the GaAs wafer is illuminated by the X-ray and reaction time is long enough.

Real-time monitoring of the solution growth of ZnO nanorods arrays by quartz microbalances and in-situ temperature sensors

“…Moreover, high-energy probing electron beams can affect nanostructures growth and add intricate artifacts such as heating, charging, production of free radicals, radiolysis, and bubbling. Electromagnetic waves can also be used, instead of electrons, as probes for obtaining real-time information on the growth of nanostructures, both at system level or at single nanostructure level29101112; however, even in these cases, the experimental set-up is complex ( e.g. requiring synchrotron accelerators) and can introduce awkward side-effects due to the high photon intensity, such as the formation of highly reactive radicals.…”

In Situ Synchrotron X‐Ray Techniques for Real‐Time Probing of Colloidal Nanoparticle Synthesis

“…The redox reaction between GaAs and AgNO 3 is prevented when the GaAs surface wetted with the AgNO 3 solution is illuminated with a 12‐keV synchrotron X‐ray beam . When the wetted surface is illuminated with an X‐ray beam of 65.02 keV, the growth of Ag nanoplates is barely influenced and nanoparticles made of new compounds including Ag 7 NO 11 (silver oxy salt) and Ag 3 AsO 4 (silver arsenate) are formed only at long illumination time . Moreover, high intensity X‐rays can induce radiolysis of solvent molecules to break their chemical bonds in solution‐phase reactions, leading to the formation of very reactive radicals that can react with precursors to change the reaction pathways for the formation of colloidal nanoparticles.…”

Synchrotron based operando surface X‐ray scattering study towards structure–activity relationships of model electrocatalysts

“…Figure S2). Having polymer (e. g. PEEK) in‐situ cells with thin, X‐ray transparent walls available, allows simultaneous collection of structural (surface or bulk crystallography, roughness) and chemical (layer composition) information . Specular XRR (X‐Ray Reflectivity) has been commonly used to study (multi)layered thin film systems and gives access to surface roughness and film thickness by probing density profiles perpendicular to the surface .…”

“…Unlike ellipsometry, XRR does not require preliminary information of the sample, such as refractive indices, and retains the signal intensity even in presence of electrolyte as an advantage of using hard X‐rays. GISAXS (Grazing Incidence Small Angle Scattering) measurements can be utilized for following surface morphological changes such as island formation . As GISAXS probes very small wave vector transfer ( Q ) values both perpendicular and parallel to the surface, it is sensitive to structures with periodicity between a few nm and a few hundreds of nm.…”