Cu doped NiO (Cu:NiO) back contact layers are inserted between FTO substrates and CuBi₂O₄ thin films to improve the performance of CuBi₂O₄ photocathodes.

The development of earth‐abundant catalysts for selective electrochemical CO₂ conversion is a central challenge. CuSn bimetallic catalysts can yield selective CO₂ reduction toward either CO or formate. This study presents oxide‐derived CuSn catalysts tunable for either product and seeks to understand the synergetic effects between Cu and Sn causing these selectivity trends. The materials undergo significant transformations under CO₂ reduction conditions, and their dynamic bulk and surface structures are revealed by correlating observations from multiple methods—X‐ray absorption spectroscopy for in situ study, and quasi in situ X‐ray photoelectron spectroscopy for surface sensitivity. For both types of catalysts, Cu transforms to metallic Cu⁰ under reaction conditions. However, the Sn speciation and content differ significantly between the catalyst types: the CO‐selective catalysts exhibit a surface Sn content of 13 at. % predominantly present as oxidized Sn, while the formate‐selective catalysts display an Sn content of ≈70 at. % consisting of both metallic Sn⁰ and Sn oxide species. Density functional theory simulations suggest that Sn^δ+ sites weaken CO adsorption, thereby enhancing CO selectivity, while Sn⁰ sites hinder H adsorption and promote formate production. This study reveals the complex dependence of catalyst structure, composition, and speciation with electrochemical bias in bimetallic Cu catalysts.

MnO_x suppresses surface recombination by enhancing band bending on BiVO₄, but direct contact with the FTO substrate provides shunting pathways.

The crystallisation of sputter-deposited, amorphous In₂O₃:H films was investigated. The influence of deposition and crystallisation parameters onto crystallinity and electron hall mobility was explored. Significant precipitation of metallic indium was discovered in the crystallised films by electron energy loss spectroscopy. Melting of metallic indium at ~160 °C was suggested to promote primary crystallisation of the amorphous In₂O₃:H films. The presence of hydroxyl was ascribed to be responsible for the recrystallization and grain growth accompanying the inter-grain In-O-In bounding. Metallic indium was suggested to provide an excess of free electrons in as-deposited In₂O₃ and In₂O₃:H films. According to the ultraviolet photoelectron spectroscopy, the work function of In₂O₃:H increased during crystallisation from 4 eV to 4.4 eV, which corresponds to the oxidation process. Furthermore, transparency simultaneously increased in the infraredspectral region. Water was queried to oxidise metallic indium in UHV at higher temperature as compared to oxygen in ambient air. Secondary ion mass-spectroscopy results revealed that the former process takes place mostly within the top ~50 nm. The optical band gap of In₂O₃:H increased by about 0.2 eV during annealing, indicating a doping effect. This was considered as a likely intra-grain phenomenon caused by both (In⁰)_O^•• and (OH⁻)_O^• point defects. The inconsistencies in understanding of In₂O₃:H crystallisation, which existed in the literature so far, were considered and explained by the multiplicity and disequilibrium of the processes running simultaneously.

The nanostructure of hydrogenated amorphous silicon (a-$\mathrm{Si}:\mathrm{H}$) is studied by a combination of small-angle x-ray scattering (SAXS) and small-angle neutron scattering (SANS) with a spatial resolution of 0.8 nm. The a-$\mathrm{Si}:\mathrm{H}$ materials were deposited using a range of widely varied conditions and are representative for this class of materials. We identify two different phases that are embedded in the a-$\mathrm{Si}:\mathrm{H}$ matrix and quantified both according to their scattering cross sections. First, 1.2 nm sized voids (multivacancies with more than 10 missing atoms) which form a superlattice with 1.6 nm void-to-void distance are detected. The voids are found in concentrations as high as $6\times {10}^{19}{\mathrm{cm}}^{-3}$ in a-$\mathrm{Si}:\mathrm{H}$ material that is deposited at a high rate. Second, dense ordered domains (DOD) that are depleted of hydrogen with 1 nm average diameter are found. The DOD tend to form 10–15 nm sized aggregates and are largely found in all a-$\mathrm{Si}:\mathrm{H}$ materials considered here. These quantitative findings make it possible to understand the complex correlation between structure and electronic properties of a-$\mathrm{Si}:\mathrm{H}$ and directly link them to the light-induced formation of defects. Finally, a structural model is derived, which verifies theoretical predictions about the nanostructure of a-$\mathrm{Si}:\mathrm{H}$.

Nickel-indium mixed oxides catalyse electrochemical CO₂ reduction with high CO selectivity (71%), contrasting NiO (H₂ > 90%) and In₂O₃ (HCOO⁻ > 80%). Dynamic structural transformations dependent on bias and time are observed during operation.