Interfacial engineering of a vertically stacked graphene/h-BN heterostructure as an efficient electrocatalyst for hydrogen peroxide synthesis

Rationally Designing Efficient Biomass Carbon Electrocatalysts for H2O2 Synthesis and Near-Neutral Zn-Air Batteries with Preliminary Machine Learning Guidance

Biomass-based carbon materials are considered promising metal-free catalysts for the 2e- oxygen reduction reaction (ORR) to synthesize H2O2 and act as air electrodes in Zn-air batteries. However, optimization of the catalyst structure is a complex process due to the diversity of biomass precursors and synthesis parameters. Machine learning, a new artificial intelligence technology, has recently been used in various fields owing to its ability to rapidly analyze large amounts of data and guide material synthesis. Consequently, we constructed a machine learning model based on previously reported experimental data and guided the fabrication of a boron-doped biomass carbon catalyst for the 2e- ORR. The achieved catalytic performance exceeded most reported ORR catalysts in terms of H2O2 selectivity (90-95% in broad potentials of 0.30-0.68 V vs reversible hydrogen electrode), stability (maintaining over 90% selectivity for 12 h), yield (3450 mmol gcatalyst-1 h-1), and Faraday efficiency (over 90%). We applied the catalysts to Zn-air batteries and showed a high capacity (2856 mAh g-1) and stability twice that of traditional commercial metal catalysts. Therefore, this study proposed an effective machine learning model to guide the fabrication of biomass-based catalysts in the field of electrocatalysis.

Enhanced Electrocatalytic Hydrogen Peroxide Production via a CuWO4/WO3 Heterojunction with High Selectivity and Stability

The electrocatalytic conversion of oxygen to hydrogen peroxide offers a promising pathway for sustainable energy production. However, the development of catalysts that are highly active, stable, and cost-effective for hydrogen peroxide synthesis remains a significant challenge. In this study, a novel polyacid-based metal-organic coordination compound (Cu-PW) was synthesized using a hydrothermal approach. Cu-PW served as a precursor to construct a composite electrocatalyst featuring a heterointerface between CuWO4 and WO3 (CuWO4/WO3) through pyrolysis. The CuWO4/WO3 heterojunction exhibits an impressive H2O2 selectivity of 91.84% at 0.5 V, marking a 19.65% improvement compared to the pristine Cu-PW. Furthermore, the CuWO4/WO3 catalyst demonstrates exceptional stability, maintaining continuous operation for 29 h. At 0.1 V, it delivers a hydrogen peroxide yield of 1537.8 mmol g-1 h-1, with a Faraday efficiency (FE) of 85%. Additionally, this catalyst effectively degrades methyl blue, achieving a 95% removal from an aqueous system within 30 min. Theoretical analysis further corroborates the high electroactivity of CuWO4/WO3 heterojunction structure. The Cu-O-W bridge formed during the reaction facilitates interfacial electron transport and enhances the role of the W-O bond in proton adsorption and transfer kinetics. This strong interfacial coupling in CuWO4/WO3 promotes electron transfer and the formation of *OOH intermediates, thereby favoring hydrogen peroxide generation. Hence, the as-prepared CuWO4/WO3 demonstrates great potential as an efficient electrocatalyst for the green synthesis of hydrogen peroxide, exhibiting high efficiency as a two-electron oxygen reduction reaction catalyst. This work offers a new approach for fabricating CuWO4/WO3 electrocatalyst with high electroactivity and selectivity, paving the way for cost-effective and sustainable hydrogen peroxide production, significantly reducing reliance on the conventional anthraquinone process.

2D/2D coupled MOF/Fe composite metamaterials enable robust ultra-broadband microwave absorption

The combination between macroscopic structure designs and microscopic material designs offers tremendous possibilities for the development of advanced electromagnetic wave (EMW) absorbers. Herein, we propose a metamaterial design to address persistent challenges in this field, including narrow bandwidth, low-frequency bottlenecks, and, particularly, the urgent issue of robustness (i.e., oblique, and polarized incidence). Our absorber features a semiconductive metal-organic framework/iron 2D/2D assembly (CuHT-FCIP) with abundant crystal/crystal heterojunctions and strong magneto-electric coupling networks. This design achieves remarkable EMW absorption across a broad range (2 to 40 GHz) at a thickness of just 9.3 mm. Notably, it maintains stable performance against oblique incidence (within 75°) and polarizations (both transverse electric and transverse magnetic). Furthermore, the absorber demonstrates high specific compressive strength (201.01 MPa·cm3·g-1) and low density (0.89 g·cm-3). This advancement holds promise for developing robust EMW absorbers with superior performance.

Carbon Catalysts Empowering Sustainable Chemical Synthesis via Electrochemical CO2 Conversion and Two-Electron Oxygen Reduction Reaction

Carbon materials hold significant promise in electrocatalysis, particularly in electrochemical CO2 reduction reaction (eCO2 RR) and two-electron oxygen reduction reaction (2e- ORR). The pivotal factor in achieving exceptional overall catalytic performance in carbon catalysts is the strategic design of specific active sites and nanostructures. This work presents a comprehensive overview of recent developments in carbon electrocatalysts for eCO2 RR and 2e- ORR. The creation of active sites through single/dual heteroatom doping, functional group decoration, topological defect, and micro-nano structuring, along with their synergistic effects, is thoroughly examined. Elaboration on the catalytic mechanisms and structure-activity relationships of these active sites is provided. In addition to directly serving as electrocatalysts, this review explores the role of carbon matrix as a support in finely adjusting the reactivity of single-atom molecular catalysts. Finally, the work addresses the challenges and prospects associated with designing and fabricating carbon electrocatalysts, providing valuable insights into the future trajectory of this dynamic field.