Ferroelectric nanomaterials offer the promise of switchable electronic properties at the surface, with implications for photo- and electrocatalysis. Studies to date on the effect of ferroelectric surfaces in electrocatalysis have been primarily limited to nanoparticle systems where complex interfaces arise. Here, we use MBE-grown epitaxial BaTiO3 thin films with atomically sharp interfaces as model surfaces to demonstrate the effect of ferroelectric polarization on the electronic structure, intermediate binding energy, and electrochemical activity toward the hydrogen evolution reaction (HER). Surface spectroscopy and ab initio DFT+U calculations of the well-defined (001) surfaces indicate that an upward polarized surface reduces the work function relative to downward polarization and leads to a smaller HER barrier, in agreement with the higher activity observed experimentally. Employing ferroelectric polarization to create multiple adsorbate interactions over a single electrocatalytic surface, as demonstrated in this work, may offer new opportunities for nanoscale catalysis design beyond traditional descriptors.

Carbon dioxide electrolysis powered by renewable energy is a potentially attractive approach to close the carbon cycle and produce key chemical feedstocks. Here, we demonstrate the substantial influence of tensile strain on the selectivity of CO2 reduction toward higher value-added, multicarbon products by modulating the residual mismatch strain of Cu(001) thin film catalysts grown epitaxially on single-crystal Si substrates. By decreasing film thickness from 100 to 20 nm, up to 0.22% tensile strain is introduced in-plane, shifting the measured Cu d-band center at the surface upward, in good agreement with theory. CO2 electrolysis at moderate overpotential (−0.9 V vs reversible hydrogen electrode (RHE)) in 0.1 M KHCO3 electrolyte reveals that the shift in d-band center results in the suppression of single-carbon products, while activity for multicarbon products is maintained. Examination of the ratio of partial current densities for multicarbon products relative to CO and CH4 suggests increased CO insertion and hydrogenation on the tensile-strained Cu(001) surface, driven by a change in the adsorbate bonding because of an increased interaction with the upshifted d-band. This work provides direct experimental evidence on model thin film CO2 catalysts that strain can be systematically manipulated as a valuable tool, independent of catalyst composition, for the design of efficient CO2 electrocatalysts toward energy-dense products.

The electrochemical conversion of CO 2 to hydrocarbons and alcohols for use as a renewable energy storage medium is a promising approach to CO 2 utilization and energy sustainability. Herein, we demonstrate that the selectivity of an electrochemically reduced Cu(OH) 2 nanowire catalyst toward C 2 −C 3 compounds (ethylene, ethanol, and npropanol) is systemically modified by surface morphology, which is governed by the electrolysis potential. The total Faradaic efficiency of CO 2 reduction to C 2 −C 3 compounds is found to be 38% at a moderate potential of −0.81 V vs RHE, and stable electrocatalytic performance is observed for 40 h of CO 2 electrolysis. Electro-and physicochemical analyses indicate that the Cu(OH) 2 nanowires are completely reduced to metallic Cu, forming a mesostructured catalyst after a few minutes of electrolysis. The shift in product selectivity is strongly correlated with this change in mesoscale catalyst morphology, offering additional dimensionality and multiple length scales for catalyst design to achieve efficient CO 2 reduction to valuable C 2 −C 3 compounds, especially alcohols.

Optimizing selective contact layers in photovoltaics is necessary to yield high-performing stable devices. However, this has been difficult for perovskites due to their complex interfacial defects that affect carrier concentrations in the active layer and charge transfer and recombination at the interface. Using vacuum thermally evaporated tin oxide as a case study, we highlight electrochemical tests that are simple yet screen device-relevant contact layer properties, making them useful for process development and quality control. Specifically, we show that cyclic voltammetry and potentiostatic chronoamperometry correlate to key performance parameters in completed devices and other material/interfacial properties relevant to devices such as shunt pathways and chemical composition. Having fast, reliable, scalable, and actionable probes of electronic properties is increasingly important as halide perovskite photovoltaics approach their theoretical limits and scale to large-area devices.

A novel conversion reaction synthesis (CRS) method was used to synthesize ZnO-supported Co nanoporous metal hybrid structures from a co-precipitated nanocomposite precursor of ZnO and Co3O4. After removal of Li2O...