Carbon dioxide electroreduction (CO2R) is being actively studied as a promising route to convert carbon emissions to valuable chemicals and fuels. However, the fraction of input CO2 that is productively reduced has typically been very low, <2% for multicarbon products; the balance reacts with hydroxide to form carbonate in both alkaline and neutral reactors. Acidic electrolytes would overcome this limitation, but hydrogen evolution has hitherto dominated under those conditions. We report that concentrating potassium cations in the vicinity of electrochemically active sites accelerates CO2 activation to enable efficient CO2R in acid. We achieve CO2R on copper at pH <1 with a single-pass CO2 utilization of 77%, including a conversion efficiency of 50% toward multicarbon products (ethylene, ethanol, and 1-propanol) at a current density of 1.2 amperes per square centimeter and a full-cell voltage of 4.2 volts.

The carbon dioxide reduction reaction (CO 2 RR) presents the opportunity to consume CO 2 and produce desirable products. However, the alkaline conditions required for productive CO 2 RR result in the bulk of input CO 2 being lost to bicarbonate and carbonate. This loss imposes a 25% limit on the conversion of CO 2 to multicarbon (C 2+ ) products for systems that use anions as the charge carrierand overcoming this limit is a challenge of singular importance to the field. Here, we find that cation exchange membranes (CEMs) do not provide the required locally alkaline conditions, and bipolar membranes (BPMs) are unstable, delaminating at the membrane−membrane interface. We develop a permeable CO 2 regeneration layer (PCRL) that provides an alkaline environment at the CO 2 RR catalyst surface and enables local CO 2 regeneration. With the PCRL strategy, CO 2 crossover is limited to 15% of the amount of CO 2 converted into products, in all cases. Low crossover and low flow rate combine to enable a single pass CO 2 conversion of 85% (at 100 mA/cm 2 ), with a C 2+ faradaic efficiency and full cell voltage comparable to the anion-conducting membrane electrode assembly.

E. H. (2022). Quantum-size-tuned heterostructures enable efficient and stable inverted perovskite solar cells. Nature Photonics.

Tin oxide (SnO2) has recently emerged as a promising electron transport layer for perovskite solar cells (PSCs) in light of the material’s optical and electronic properties and its low-temperature processing. However, SnO2 films are prone to surface defect formation, which results in energy loss in PSCs. We report that surface treatment using ammonium fluoride (NH4F) leads to reduced surface defects and that it also induces chemical doping of the SnO2 substrate simultaneously. The effects of NH4F treatment on SnO2 properties are revealed by surface chemical analysis, computational studies, and energy level investigations, and PSCs with the treatment achieve photovoltaic performance of 23.2% in light of higher voltage than in relevant controls.

The all‐inorganic nature of CsPbI3 perovskites allows to enhance stability in perovskite devices. Research efforts have led to improved stability of the black phase in CsPbI3 films; however, these strategies—including strain and doping—are based on organic‐ligand‐capped perovskites, which prevent perovskites from forming the close‐packed quantum dot (QD) solids necessary to achieve high charge and thermal transport. We developed an inorganic ligand exchange that leads to CsPbI3 QD films with superior phase stability and increased thermal transport. The atomic‐ligand‐exchanged QD films, once mechanically coupled, exhibit improved phase stability, and we link this to distributing strain across the film. Operando measurements of the temperature of the LEDs indicate that KI‐exchanged QD films exhibit increased thermal transport compared to controls that rely on organic ligands. The LEDs exhibit a maximum EQE of 23 % with an electroluminescence emission centered at 640 nm (FWHM: ≈31 nm). These red LEDs provide an operating half‐lifetime of 10 h (luminance of 200 cd m−2) and an operating stability that is 6× higher than that of control devices.

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We report formate production via CO2 electroreduction at a Faradaic efficiency (FE) of 93% and a partial current density of 930 mA cm -2 , an activity level of potential industrial interest based on prior techno-economic analyses. We devise a novel catalyst synthesized using InP colloidal quantum dots (CQDs): the capping ligand exchange introduces surface sulfur, and XPS reveals the generation, operando, of an active catalyst exhibiting sulfur-protected oxidized indium and indium metal. Surface indium metal sites adsorb and reduce CO2 molecules, while

The open‐circuit voltage (Voc) of perovskite solar cells is limited by non‐radiative recombination at perovskite/carrier transport layer (CTL) interfaces. 2D perovskite post‐treatments offer a means to passivate the top interface; whereas, accessing and passivating the buried interface underneath the perovskite film requires new material synthesis strategies. It is posited that perovskite ink containing species that bind strongly to substrates can spontaneously form a passivating layer with the bottom CTL. The concept using organic spacer cations with rich NH2 groups is implemented, where readily available hydrogens have large binding affinity to under‐coordinated oxygens on the metal oxide substrate surface, inducing preferential crystallization of a thin 2D layer at the buried interface. The passivation effect of this 2D layer is examined using steady‐state and time‐resolved photoluminescence spectroscopy: the 2D interlayer suppresses non‐radiative recombination at the buried perovskite/CTL interface, leading to a 72% reduction in surface recombination velocity. This strategy enables a 65 mV increase in Voc for NiOx based p–i–n devices, and a 100 mV increase in Voc for SnO2‐based n–i–p devices. Inverted solar cells with 20.1% power conversion efficiency (PCE) for 1.70 eV and 22.9% PCE for 1.55 eV bandgap perovskites are demonstrated.