Cu oxides catalyze the electrochemical carbon dioxide reduction reaction (CO2RR) to hydrocarbons and oxygenates with favorable selectivity. Among them, the shape-controlled Cu oxide cubes have been most widely studied. In contrast, we report on novel 2-dimensional (2D) Cu(II) oxide nanosheet (CuO NS) catalysts with high C2+ products, selectivities (> 400 mA cm−2) in gas diffusion electrodes (GDE) at industrially relevant currents and neutral pH. Under applied bias, the (001)-orientated CuO NS slowly evolve into highly branched, metallic Cu0 dendrites that appear as a general dominant morphology under electrolyte flow conditions, as attested by operando X-ray absorption spectroscopy and in situ electrochemical transmission electron microscopy (TEM). Millisecond-resolved differential electrochemical mass spectrometry (DEMS) track a previously unavailable set of product onset potentials. While the close mechanistic relation between CO and C2H4 was thereby confirmed, the DEMS data help uncover an unexpected mechanistic link between CH4 and ethanol. We demonstrate evidence that adsorbed methyl species, *CH3, serve as common intermediates of both CH3H and CH3CH2OH and possibly of other CH3-R products via a previously overlooked pathway at (110) steps adjacent to (100) terraces at larger overpotentials. Our mechanistic conclusions challenge and refine our current mechanistic understanding of the CO2 electrolysis on Cu catalysts.

Stable emission in glass Lead halide perovskites can exhibit bright, narrow band photoluminescence but have stability issues related to formation of inactive phases and the loss of lead ions. Hou et al . show that the black, photoactive phase of cesium lead iodide can be stabilized by forming a composite with a glassy phase of a metal-organic framework through liquid-phase sintering. The photoluminescence is at least two orders of magnitude greater than that of the pure perovskite. The glass stabilizes the perovskite under high laser excitation, and about 80% of the photoluminescence was maintained after 10,000 hours of water immersion. —PDS

No abstract

Bidentate phosphonate monoesters are analogues of popular dicarboxylate linkers in MOFs, but with an alkoxy tether close to the coordinating site. Herein, we report 3-D MOF materials based upon phosphonate monoester linkers. Cu(1,4-benzenediphosphonate bis(monoalkyl ester), CuBDPR, with an ethyl tether is nonporous; however, the methyl tether generates an isomorphous framework that is porous and captures CO(2) with a high isosteric heat of adsorption of 45 kJ mol(-1). Computational modeling reveals that the CO(2) uptake is extremely sensitive both to the flexing of the structure and to the orientation of the alkyl tether.

The processes leading to degradation of Pt nanoparticles inside commercial hydrogen fuel cell catalyst layers are studied in situ, using time-resolved high-energy powder X-ray diffraction. Advances in electrochemical cell design significantly increase the quality of diffraction patterns obtained at practical catalyst loadings at high temporal resolution and allow the use of advanced techniques including differential pair distribution function analysis. Rietveld refinement of the lattice parameter and peak intensities during cyclic voltammetry or potential steps allow the separate steps of oxygen electroadsorption and place exchange in the Pt oxide growth mechanism to be clearly differentiated. The slow kinetics of the place-exchange process limit the oxide growth under standard laboratory conditions, decoupling the surface chemistry of the nanoparticles from the applied potential and directly affecting the outcome of accelerated stress tests measured with different cycling schemes. High-speed diffraction measurements are also used to follow the oxide reduction reaction, which is much faster. Refined structural parameters from these data show direct evidence for a transient, disordered platinum intermediate created during reduction of the oxide, which is likely responsible for catalyst dissolution when cycling to high potentials.