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Abstract Producing valuable chemicals like ethylene via catalytic carbon monoxide conversion is an important nonpetroleum route. Here we demonstrate an electrochemical route for highly efficient synthesis of multicarbon (C2+) chemicals from CO. We achieve a C2+ partial current density as high as 4.35 ± 0.07 A cm−2 at a low cell voltage of 2.78 ± 0.01 V over a grain boundary-rich Cu nanoparticle catalyst in an alkaline membrane electrode assembly (MEA) electrolyzer, with a C2+ Faradaic efficiency of 87 ± 1% and a CO conversion of 85 ± 3%. Operando Raman spectroscopy and density functional theory calculations reveal that the grain boundaries of Cu nanoparticles facilitate CO adsorption and C − C coupling, thus rationalizing a qualitative trend between C2+ production and grain boundary density. A scale-up demonstration using an electrolyzer stack with five 100 cm2 MEAs achieves high C2+ and ethylene formation rates of 118.9 mmol min−1 and 1.2 L min−1, respectively, at a total current of 400 A (4 A cm−2) with a C2+ Faradaic efficiency of 64%.

Abstract In heterogeneous catalysis catalyst activation is often observed during the reaction process, which is mostly attributed to the induction by reactants. In this work we report that surface structure of molybdenum nitride (MoN x ) catalyst exhibits a high dependency on the partial pressure or concentration of reaction products i.e., CO and H2O in reverse water gas-shift reaction (RWGS) (CO2:H2 = 1:3) but not reactants of CO2 and H2. Molybdenum oxide (MoO x ) overlayers formed by oxidation with H2O are observed at reaction pressure below 10 mbar or with low partial pressure of CO/H2O products, while CO-induced surface carbonization happens at reaction pressure above 100 mbar and with high partial pressure of CO/H2O products. The reaction products induce restructuring of MoN x surface into more active molybdenum carbide (MoC x ) to increase the reaction rate and make for higher partial pressure CO, which in turn promote further surface carbonization of MoN x . We refer to this as the positive feedback between catalytic activity and catalyst activation in RWGS, which should be widely present in heterogeneous catalysis.

Abstract The limited surface coverage and activity of active hydrides on oxide surfaces pose challenges for efficient hydrogenation reactions. Herein, we quantitatively distinguish the long-puzzling homolytic dissociation of hydrogen from the heterolytic pathway on Ga2O3, that is useful for enhancing hydrogenation ability of oxides. By combining transient kinetic analysis with infrared and mass spectroscopies, we identify the catalytic role of coordinatively unsaturated Ga3+ in homolytic H2 dissociation, which is formed in-situ during the initial heterolytic dissociation. This site facilitates easy hydrogen dissociation at low temperatures, resulting in a high hydride coverage on Ga2O3 (H/surface Ga3+ ratio of 1.6 and H/OH ratio of 5.6). The effectiveness of homolytic dissociation is governed by the Ga-Ga distance, which is strongly influenced by the initial coordination of Ga3+. Consequently, by tuning the coordination of active Ga3+ species as well as the coverage and activity of hydrides, we achieve enhanced hydrogenation of CO2 to CO, methanol or light olefins by 4-6 times.

Abstract Molybdenum supported on zeolites has been extensively studied as a catalyst for methane dehydroaromatization. Despite significant progress, the actual intermediates and particularly the first C-C bond formation have not yet been elucidated. Herein we report evolution of methyl radicals during non-oxidative methane activation over molybdenum single sites, which leads selectively to value-added chemicals. Operando X-ray absorption spectroscopy and online synchrotron vacuum ultraviolet photoionization mass spectroscopy in combination with electron microscopy and density functional theory calculations reveal the essential role of molybdenum single sites in the generation of methyl radicals and that the formation rate of methyl radicals is linearly correlated with the number of molybdenum single sites. Methyl radicals transform to ethane in the gas phase, which readily dehydrogenates to ethylene in the absence of zeolites. This is essentially similar to the reaction pathway over the previously reported SiO2 lattice-confined single site iron catalyst. However, the availability of a zeolite, either in a physical mixture or as a support, directs the subsequent reaction pathway towards aromatization within the zeolite confined pores, resulting in benzene as the dominant hydrocarbon product. The findings reveal that methyl radical chemistry could be a general feature for metal single site catalysis regardless of the support (either zeolites MCM-22 and ZSM-5 or SiO2) whereas the reaction over aggregated molybdenum carbide nanoparticles likely facilitates carbon deposition through surface C-C coupling. These findings allow furthering the fundamental insights into non-oxidative methane conversion to value-added chemicals.

Perovskites with in situ exsolved metal nanoparticles have been extensively studied for CO2 electrolysis in solid oxide electrolysis cell. However, exsolution process is strongly governed by the sluggish diffusion rate of cations and poor structural stability issues. Here we present a new exsolution process on redox stable Pr0.7Sr0.3Cr0.9Ni0.1O3−δ (PSCN) perovskite by topotactic exsolution. This process tends to generate host stoichiometric Pr0.7Sr0.3Cr0.9(FeNi)0.1O3−δ perovskite, triggering Ni cations segregation from the host while maintaining structural stability via supplement of Fe guest cations. The FeNi alloy nanoparticles decorated cathode showed a current density of 1.49 A cm−2 at 800 °C and 1.6 V for CO2 electrolysis, demonstrating over 62.0 % improvement compared to the primitive PSCN cathode. Experimental studies and density functional theory calculations revealed that the activity originated from the unique ability to adsorb and activate CO2 at the metal/perovskite interfaces. This cation supplement strategy may expand the frontiers in the evolution of exsolution on perovskite catalysts for CO2 utilization and other heterogeneous catalytic reactions.

Great progress has been made in the development of bifunctional oxide-zeolite catalysts to tackle the selectivity challenge in syngas chemistry. Here the authors show syngas conversion can be steered along a highly active and selective pathway towards light olefins via ketene acetate (acetyl) intermediates.

Achieving CO oxidation at room temperature is significant for gas purification but remains challenging to perform. Here, the authors report design of graphene-isolated Pt from cobalt-nickel nanoparticles for efficiently catalytic CO oxidation in an oxygen-rich atmosphere.

Metal nanoparticles anchored on perovskite provide catalytically active interfaces for CO2 electrolysis. The authors promote exsolution of RuFe alloy nanoparticles on Sr2Fe1.4Ru0.1Mo0.5 O6−δ perovskite by enriching the active Ru underneath the perovskite surface via repeated redox manipulations.

Cubic perovskite oxides usually suffer from delamination and Sr2+ segregation for catalyzing oxygen evolution reaction (OER) at the anodes of solid oxide electrolysis cells (SOECs). It is crucial to develop alternative and efficient anode materials for SOECs. Herein, a series of novel Y0.95-xSrxCo0.3Fe0.7O3-δ (YSCF-x) orthorhombic perovskite oxides in the Pnma (62) space group are synthesized as anode materials of SOECs. Physicochemical characterizations and density functional theory calculations reveal that the partial substitution of Y3+ by Sr2+ increases the oxygen vacancy concentration and mobility as well as improves the electrical conductivity, which contributes to the excellent OER activity of YSCF-x. At 800 °C, the current density of SOEC with YSCF-0.05-Ce0.8Sm0.2O2-δ anode can reach 1.32 A cm−2 at 1.6 V, about twice that of SOEC with Y0.95Co0.3Fe0.7O3-δ-Ce0.8Sm0.2O2-δ anode. This work paves a new avenue for the design of advanced anode materials of SOECs.

Designing ultra small metal nanoclusters or single atoms with metallic state is a challenge. Here, the authors demonstrate the stabilization of ultra small silver clusters in the nearly-metallic state by oxygen adsorption at high temperature, using in situ spectroscopy and microscope technologies.

The design of oxide-metal interface for heterogeneous catalysis has been hampered by the limited fundamental understanding. Here, the authors demonstrate that the activities of cuprous oxide nanostructures for CO oxidation can be tuned via the oxide-metal (Cu2O/M, M = Pt, Ag, Au) interaction.

Loading guests inside the pre-existing pores of nanoporous hosts remains challenging. Here, the authors introduce a rational route for incorporation of guest compounds into an arbitrary nanoporous host, enabling the investigation of multiple host-guest systems with surprising functionalities.

Traditional water–gas shift reaction process is hindered by harsh reaction conditions and extra steps for hydrogen separation and purification. Here, the authors report a room temperature electrochemical water–gas shift process for direct production of high purity hydrogen with a faradaic efficiency of approximately 100%.

Broadband photodetectors for various applications are in high demand, however, often suffering from non-linearities at high power densities. Here, a reduced strontium titanate based photodetector exhibiting linear response up to 1235 W/cm2 is presented not achieved by other broadband photodetectors.

Strain and support effects play a crucial role in heterogeneous catalysis, which has been intensively studied over metal-based catalysts. In contrast, there is little discussion about the two effects in oxide systems. In this work, using an ultrathin ZnO film as an example, we investigate strain and support effects on the structure and surface reactivity of oxide catalysts through density functional theory calculations. Our results suggest that tensile strain increases the surface reactivity of ZnO films as indicated by enhanced CO and NH3 adsorptions and compressive strain renders an early phase transition from an inert graphene-like phase to a more reactive wurtzite-like phase. The support (Au, Pt, and Ru) can promote the phase transition and surface reactivity concurrently, which exhibits a larger effect on the reactivity than the strain. The support effect can be ascribed to the increasing rumple and polarization of ZnO films through the strong ZnO–substrate interaction, which enhances the surface reactivity. The insight helps us to develop advanced oxide-based catalysts through the strain and/or substrate engineering.

Abstract Single‐atom catalysts (SACs) are efficient for maximizing electrocatalytic activity, but have unsatisfactory activity for the oxygen evolution reaction (OER). Herein, the NaCl template synthesis of individual nickel (Ni) SACs is reported, bonded to oxygen sites on graphene‐like carbon (denoted as Ni‐O‐G SACs) with superior activity and stability for OER. A variety of characterizations unveil that the Ni‐O‐G SACs present 3D porous framework constructed by ultrathin graphene sheets, single Ni atoms, coordinating nickel atoms to oxygen. Consequently, the catalysts are active and robust for OER with extremely low overpotential of 224 mV at current density of 10 mA cm−2, 42 mV dec−1 Tafel slope, oxygen production turn over frequency of 1.44 S−1 at 300 mV, and long‐term durability without significant degradation for 50 h at exceptionally high current of 115 mA cm−1, outperforming the state‐of‐the‐art OER SACs. A theoretical simulation further reveals that the bonding between single nickel and oxygen sites results in the extraordinary boosting of OER performance of Ni‐O‐G SACs. Therefore, this work opens numerous opportunities for creating unconventional SACs via metal–oxygen bonding.

Abstract With the relentless development of smart and miniaturized electronics, the worldwide thirst for microscale electrochemical energy storage devices with form factors is launching a new era of competition. Herein, the first prototype planar sodium‐ion microcapacitors (NIMCs) are constructed based on the interdigital microelectrodes of urchin‐like sodium titanate as faradaic anode and nanoporous activated graphene as non‐faradaic cathode along with high‐voltage ionogel electrolyte on a single flexible substrate. By effectively coupling with battery‐type anode and capacitor‐type cathode, the resultant all‐solid‐state NIMCs working at 3.5 V exhibit a high volumetric energy density of 37.1 mWh cm−3 and an ultralow self‐discharge rate of 44 h from Vmax to 0.6 Vmax, both of which surpass most reported hybrid micro‐supercapacitors. Through tuning graphene layer covered on the top surface of interdigital microelectrodes, the NIMCs unveil remarkably enhanced power density, owing to the establishment of favorable multidirectional fast ion diffusion pathways that significantly reduce the charge transfer resistance. Meanwhile, the as‐fabricated NIMCs present excellent mechanical flexibility without capacitance fade under repeated deformation, and electrochemical stability at a high temperature of 80 °C because of using nonflammable ionogel electrolyte and in‐plane geometry. Therefore, these flexible planar NIMCs with multidirectional ion diffusion pathways hold tremendous potential for microelectronics.

The origin of interface charge transfer and electron-phonon coupling in single unit-cell FeSe on SrTiO3 remains elusive. Here, Zhang et al. report strengthened Ti-O bond and band bending at the FeSe/SrTiO3 interface, which leads to several important processes.

The hydrogen evolution reaction is a complicated process involving liquid-solid-gas three-phase interface behaviour. Here, the authors report the multiscale structural and electronic control of molybdenum disulfide foam and demonstrate its high activity and stability for hydrogen evolution.

Smaller nanostructures often have higher activities, but at the expense of losing chemical stability. Here, the authors find that reducing the size of FeO nanostructures to below 3 nm enhances their resistance to oxidation, and attribute this unexpected observation to a size-dependent, structural dynamics effect.

Metals supported on metal oxides are common heterogeneous catalysts. Here the authors show that metal/oxide interfacial sites are highly active for alcohol oxidation—independent of the particle sizes—and use this information to design inverse oxide-on-metal particles with high activity and stability.