The electrochemical reduction of carbon dioxide (CO 2 RR) offers a compelling route to energy storage and high-value chemical manufacture. The presence of sulfur atoms in catalyst surfaces promotes undercoordinated sites, thereby improving the electrochemical reduction of CO 2 to formate. The resulting sulfurmodulated tin catalysts accelerate CO 2 RR at geometric current densities of 55 mA cm À2 at À0.75 V versus RHE with a Faradaic efficiency of 93%.
Efficient wide-bandgap perovskite solar cells (PSCs) enable high-efficiency tandem photovoltaics when combined with crystalline silicon and other low-bandgap absorbers. However, wide-bandgap PSCs today exhibit performance far inferior to that of sub-1.6-eV bandgap PSCs due to their tendency to form a high density of deep traps. Here, we show that healing the deep traps in wide-bandgap perovskites—in effect, increasing the defect tolerance via cation engineering—enables further performance improvements in PSCs. We achieve a stabilized power conversion efficiency of 20.7% for 1.65-eV bandgap PSCs by incorporating dipolar cations, with a high open-circuit voltage of 1.22 V and a fill factor exceeding 80%. We also obtain a stabilized efficiency of 19.1% for 1.74-eV bandgap PSCs with a high open-circuit voltage of 1.25 V. From density functional theory calculations, we find that the presence and reorientation of the dipolar cation in mixed cation–halide perovskites heals the defects that introduce deep trap states.
In
hydrogen production, the anodic oxygen evolution reaction (OER)
limits the energy conversion efficiency and also impacts stability
in proton-exchange membrane water electrolyzers. Widely used Ir-based
catalysts suffer from insufficient activity, while more active Ru-based
catalysts tend to dissolve under OER conditions. This has been associated
with the participation of lattice oxygen (lattice oxygen oxidation
mechanism (LOM)), which may lead to the collapse of the crystal structure
and accelerate the leaching of active Ru species, leading to low operating
stability. Here we develop Sr–Ru–Ir ternary oxide electrocatalysts
that achieve high OER activity and stability in acidic electrolyte.
The catalysts achieve an overpotential of 190 mV at 10 mA cm–2 and the overpotential remains below 225 mV following 1,500 h of
operation. X-ray absorption spectroscopy and 18O isotope-labeled
online mass spectroscopy studies reveal that the participation of
lattice oxygen during OER was suppressed by interactions in the Ru–O–Ir
local structure, offering a picture of how stability was improved.
The electronic structure of active Ru sites was modulated by Sr and
Ir, optimizing the binding energetics of OER oxo-intermediates.
Chemicals manufacturing consumes large amounts of energy and is responsible for a substantial portion of global carbon emissions. Electrochemical systems that produce the desired compounds by using renewable electricity offer a route to lower carbon emissions in the chemicals sector. Ethylene oxide is among the world’s most abundantly produced commodity chemicals because of its importance in the plastics industry, notably for manufacturing polyesters and polyethylene terephthalates. We applied an extended heterogeneous:homogeneous interface, using chloride as a redox mediator at the anode, to facilitate the selective partial oxidation of ethylene to ethylene oxide. We achieved current densities of 1 ampere per square centimeter, Faradaic efficiencies of ~70%, and product specificities of ~97%. When run at 300 milliamperes per square centimeter for 100 hours, the system maintained a 71(±1)% Faradaic efficiency throughout.
Producing liquid fuels such as ethanol from CO2, H2O, and renewable electricity offers a route to store sustainable energy. The search for efficient electrocatalysts for the CO2 reduction reaction relies on tuning the adsorption strength of carbonaceous intermediates. Here, we report a complementary approach in which we utilize hydroxide and oxide doping of a catalyst surface to tune the adsorbed hydrogen on Cu. Density functional theory studies indicate that this doping accelerates water dissociation and changes the hydrogen adsorption energy on Cu. We synthesize and investigate a suite of metal-hydroxide-interface-doped-Cu catalysts, and find that the most efficient, Ce(OH)x-doped-Cu, exhibits an ethanol Faradaic efficiency of 43% and a partial current density of 128 mA cm−2. Mechanistic studies, wherein we combine investigation of hydrogen evolution performance with the results of operando Raman spectroscopy, show that adsorbed hydrogen hydrogenates surface *HCCOH, a key intermediate whose fate determines branching to ethanol versus ethylene.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.