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The co‐electroreduction of CO2 and NOx⁻ (NO3⁻/NO2⁻) to generate formamide (HCONH2) offers an opportunity for downstream chemical and polymer manufacturing decarbonization; however, significant challenges lie in the C‒N coupling and the associated low product selectivity. Herein, p‐block metal oxides are incorporated in copper oxides to provide more accessible active sites for reactant adsorption and activation, tuning the reaction selectivity toward the formamide production. Through in situ Raman and synchrotron‐based infrared spectroscopy measurements, C─N bond formation is demonstrated in real‐time with the CuOx/BiOx catalyst, where the C─N bond is detected via a *CHO and *NH2 intermediates formation, in agreement with the density functional theory calculations. When tested in a flow electrolyzer, a formamide yield rate of 134 ± 11 mmol h−1 gcat−1 is reported, the first report of co‐electroreduction of CO2 and NOx⁻ to formamide beyond conventional H‐cell measurements. These new insights on the C‒N coupling mechanisms and scale‐up capability provide directions for further development of electrocatalysts for the formamide production. [ABSTRACT FROM AUTHOR]

Over 79 % of 6.3 billion tonnes of plastics produced from 1950 to 2015 have been disposed in landfills or found their way to the oceans, where they will reside for up to hundreds of years before being decomposed bringing upon significant dangers to our health and ecosystems. Plastic photoreforming offers an appealing alternative by using solar energy and water to transform plastic waste into value‐added chemical commodities, while simultaneously producing green hydrogen via the hydrogen evolution reaction. This review aims to provide an overview of the underlying principles of emerging plastic photoreforming technologies, highlight the challenges associated with experimental protocols and performance assessments, discuss recent global breakthroughs on the photoreforming of plastics, and propose perspectives for future research. A critical assessment of current plastic photoreforming studies shows a lack of standardised conditions, hindering comparison amongst photocatalyst performance. Guidelines to establish a more accurate evaluation of materials and systems are proposed, with the aim to facilitate the translation of promising fundamental discovery in photocatalysts design. [ABSTRACT FROM AUTHOR]

Coupling the hydrogen evolution reaction with plastic waste photoreforming provides a synergistic path for simultaneous production of green hydrogen and recycling of post‐consumer products, two major enablers for establishment of a circular economy. Graphitic carbon nitride (g‐C3N4) is a promising photocatalyst due to its suitable optoelectronic and physicochemical properties, and inexpensive fabrication. Herein, a mechanistic investigation of the structure‐activity relationship of g‐C3N4 for poly(ethylene terephthalate) (PET) photoreforming is reported by carefully controlling its fabrication from a subset of earth‐abundant precursors, such as dicyandiamide, melamine, urea, and thiourea. These findings reveal that melamine‐derived g‐C3N4 with 3 wt.% Pt has significantly higher performance than alternative derivations, achieving a maximum hydrogen evolution rate of 7.33 mmolH2 gcat−1 h−1, and simultaneously photoconverting PET into valuable organic products including formate, glyoxal, and acetate, with excellent stability for over 30 h of continuous production. This is attributed to the higher crystallinity and associated chemical resistance of melamine‐derived g‐C3N4, playing a major role in stabilization of its morphology and surface properties. These new insights on the role of precursors and structural properties in dictating the photoactivity of g‐C3N4 set the foundation for the further development of photocatalytic processes for combined green hydrogen production and plastic waste reforming. [ABSTRACT FROM AUTHOR]

The electrocatalytic recycling of waste nitrate (NO3RR) is a promising decentralized route for green ammonia synthesis. Nonetheless, it suffers from the competing hydrogen evolution reaction and the insufficient proton supply in high pH conditions. Herein, iron oxide nanoparticles anchored on ZnO is introduced as a strategy to enhance the water dissociation ability and proton transfer rate, advancing NH4+ production from alkaline NO3RR. Supported by a set of ex situ and in situ characterization, the findings reveal the reduction of iron oxides, along with improvements in charge transfer properties and proton generation from H2O. Theoretical calculations show that iron oxides reduce the kinetic barrier of the rate‐limiting step (*NO2‐to‐*NO2H) and result in a thermodynamically favorable process to hydrogenation steps, which in turn reduce the overall energy barrier of alkaline NO3RR. Optimal catalytic activity is realized with a Fe loading of 0.5 wt.%, delivering a Faradaic efficiency of ≈83% for ammonium with a NH4+ yield rate of 31 nmol s−1 cm−2 at −0.7 V versus RHE. The results pave the way for the utilization of bi‐metal interaction to tune the reaction pathway for achieving sustainable ammonium synthesis in alkaline, contributing to ongoing efforts to achieve a sustainable nitrogen cycle via N‐based electrochemistry. [ABSTRACT FROM AUTHOR]

Illuminating thermal catalysts with visible light is an effective strategy to reduce the thermal requirements of CO 2 methanation. In this study, we systematically varied the cobalt loading and properties of xCo/CeO 2 catalysts (between 0 and 10 wt%) to understand changes in the visible light-assisted reaction mechanism with cobalt loading. 10Co/CeO 2 had the highest CO 2 conversion of 90% at 450 °C. The light promoted the CO 2 conversion of all catalysts from 300 to 450°C, peaking for 7.5Co/CeO 2 with a 125% improvement relative to thermal conditions (300 °C) before diminishing for 10Co/CeO 2. The light facilitated the conversion of the formate intermediate adsorbed onto CeO 2. In-situ DRIFTS and DFT unveiled a particle size trade-off between maximising CO 2 adsorbed at the Co-Ce interface while minimising CO 2 adsorbed onto cobalt, which is required for the best light enhancement. These findings underscore the importance of careful deposit size optimisation to unlock the light-assisted methanation's full potential. [Display omitted] • Contribution of visible light can be maximised with an optimal deposit size. • CO 2 adsorption onto large cobalt deposits limits the contribution of visible light. • Trade-off between CO 2 and H 2 on cobalt deposits required for best photo-enhancement. • One-step flame spray pyrolysis made Co/CeO2 with controllable deposit sizes by varying Co loading. [ABSTRACT FROM AUTHOR]

Over 79 % of 6.3 billion tonnes of plastics produced from 1950 to 2015 have been disposed in landfills or found their way to the oceans, where they will reside for up to hundreds of years before being decomposed bringing upon significant dangers to our health and ecosystems. Plastic photoreforming offers an appealing alternative by using solar energy and water to transform plastic waste into value-added chemical commodities, while simultaneously producing green hydrogen via the hydrogen evolution reaction. This review aims to provide an overview of the underlying principles of emerging plastic photoreforming technologies, highlight the challenges associated with experimental protocols and performance assessments, discuss recent global breakthroughs on the photoreforming of plastics, and propose perspectives for future research. A critical assessment of current plastic photoreforming studies shows a lack of standardised conditions, hindering comparison amongst photocatalyst performance. Guidelines to establish a more accurate evaluation of materials and systems are proposed, with the aim to facilitate the translation of promising fundamental discovery in photocatalysts design., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Amidst these growing sustainability concerns, producing NH 4 + via electrochemical NO 3 - reduction reaction (NO 3 RR) emerges as a promising alternative to the conventional Haber-Bosch process. In a pioneering approach, this study introduces Ru incorporation into Co 3 O 4 lattices at the nanoscale and further couples it with electroreduction conditioning (ERC) treatment as a strategy to enhance metal oxide reducibility and induce oxygen vacancies, advancing NH 4 + production from NO 3 RR. Here, supported by a suite of ex situ and in situ characterization measurements, the findings reveal that Ru enrichment promotes Co species reduction and oxygen vacancy formation. Further, as evidenced by the theoretical calculations, Ru integration lowers the energy barrier for oxygen vacancy formation, thereby facilitating a more energy-efficient NO 3 RR-to-NH 4 + pathway. Optimal catalytic activity is realized with a Ru loading of 10 at.% (named 10Ru/Co 3 O 4 ), achieving a high NH 4 + production rate (98 nmol s -1  cm -2 ), selectivity (97.5%) and current density (≈100 mA cm -2 ) at -1.0 V vs RHE. The findings not only provide insights into defect engineering via the incorporation of secondary sites but also lay the groundwork for innovative catalyst design aimed at improving NH 4 + yield from NO 3 RR. This research contributes to the ongoing efforts to develop sustainable electrochemical processes for nitrogen cycle management., (© 2024 The Authors. Small published by Wiley‐VCH GmbH.)

Copper-based catalysts exhibit high activity in electrochemical CO 2 conversion to value-added chemicals. However, achieving precise control over catalysts design to generate narrowly distributed products remains challenging. Herein, a gallium (Ga) liquid metal-based approach is employed to synthesize hierarchical nanoporous copper (HNP Cu) catalysts with tailored ligament/pore and crystallite sizes. The nanoporosity and polycrystallinity are generated by dealloying intermetallic CuGa 2 formed after immersing pristine Cu foil in liquid Ga in a basic or acidic solution. The liquid metal-based approach allows for the transformation of monocrystalline Cu to the polycrystalline HNP Cu with enhanced CO 2 reduction reaction (CO 2 RR) performance. The dealloyed HNP Cu catalyst with suitable crystallite size (22.8 nm) and nanoporous structure (ligament/pore size of 45 nm) exhibits a high Faradaic efficiency of 91% toward formate production under an applied potential as low as -0.3 V RHE . The superior CO 2 RR performance can be ascribed to the enlarged electrochemical catalytic surface area, the generation of preferred Cu facets, and the rich grain boundaries by polycrystallinity. This work demonstrates the potential of liquid metal-based synthesis for improving catalysts performance based on structural design, without increasing compositional complexity., (© 2024 The Author(s). Small published by Wiley‐VCH GmbH.)

Conventional H 2 -O 2 fuel cells suffer from the low output voltage, insufficient durability, and high-cost catalysts (e.g., noble metals). Herein, this work reports a conceptually new coupled flow fuel cell (CF-FC) by coupling asymmetric electrolytes for acidic oxygen reduction reaction and alkaline hydrogen oxidation reaction. By introducing an electrochemical neutralization energy, the newly-developed CF-FCs possess a significantly increased theoretical open-circuit voltage. Specifically, a CF-FC based on a typical transition metal single-atom Fe-N-C cathode catalyst demonstrates a high electricity output up to 1.81 V and durability with an ultrahigh retention of 91% over 110 h, far superior to the conventional fuel cells (usually, < 1.0 V, < 50% retention over 20 h). The output performance can even be significantly enhanced easily by connecting multiple CF-FCs into the parallel, series, or combined parallel-series connections at a fractional cost of that for the conventional H 2 -O 2 fuel cells, showing great potential for large-scale practical applications. Thus, this study provides a platform to transform conventional fuel cell technology through the rational design and development of advanced energy conversion and storage devices by coupling different electrocatalytic reactions., (© 2024 Wiley‐VCH GmbH.)

Coupling the hydrogen evolution reaction with plastic waste photoreforming provides a synergistic path for simultaneous production of green hydrogen and recycling of post-consumer products, two major enablers for establishment of a circular economy. Graphitic carbon nitride (g-C 3 N 4 ) is a promising photocatalyst due to its suitable optoelectronic and physicochemical properties, and inexpensive fabrication. Herein, a mechanistic investigation of the structure-activity relationship of g-C 3 N 4 for poly(ethylene terephthalate) (PET) photoreforming is reported by carefully controlling its fabrication from a subset of earth-abundant precursors, such as dicyandiamide, melamine, urea, and thiourea. These findings reveal that melamine-derived g-C 3 N 4 with 3 wt.% Pt has significantly higher performance than alternative derivations, achieving a maximum hydrogen evolution rate of 7.33 mmol H2  g cat -1  h -1 , and simultaneously photoconverting PET into valuable organic products including formate, glyoxal, and acetate, with excellent stability for over 30 h of continuous production. This is attributed to the higher crystallinity and associated chemical resistance of melamine-derived g-C 3 N 4 , playing a major role in stabilization of its morphology and surface properties. These new insights on the role of precursors and structural properties in dictating the photoactivity of g-C 3 N 4 set the foundation for the further development of photocatalytic processes for combined green hydrogen production and plastic waste reforming., (© 2023 The Authors. Small Methods published by Wiley-VCH GmbH.)