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Scalable approaches for synthesis and integration of proton selective atomically thin 2D materials with proton conducting polymers can enable next-generation proton exchange membranes with minimal crossover while retaining adequate proton conductance. 

Abstract Monolayer graphene growth on liquid copper (Cu) has attracted attention due to advantages of a flat/smooth catalytic growth surface, high synthesis temperature (>1080 °C) as well as the possibility of forming graphene domains that are mobile on the liquid Cu with potential to minimize grain boundary defects and self-assemble into a continuous monolayer film. However, the quality of monolayer graphene grown on liquid copper and its suitability for size-selective ionic/molecular membrane separations has not been evaluated/studied. Here, we probe the quality of monolayer graphene grown on liquid Cu (via a metallurgical process, HSMG^®) using Scanning Electron Microscope (SEM), High-resolution transmission electron microscope (HR-TEM), Raman spectroscopy and report on a facile approach to assess intrinsic sub-nanometer to nanometer-scale defects over centimeter-scale areas. We demonstrate high transfer yields of monolayer graphene (>93% coverage) from the growth substrate to polyimide track etched membrane (PITEM, pore diameter ∼200 nm) supports to form centimeter-scale atomically thin membranes. Next, we use pressure-driven transport of ethanol to probe defects > 60 nm and diffusion-driven transport of analytes (KCl ∼0.66 nm, L-Tryptophan ∼0.7–0.9 nm, Vitamin B12 ∼1–1.5 nm and Lysozyme ∼3.8–4 nm) to probe nanoscale and sub-nanometer scale defects. Diffusive transport confirms the presence of intrinsic sub-nanometer to nanometer scale defects in monolayer graphene grown on liquid Cu are no less than that in high-quality graphene synthesized via chemical vapor deposition (CVD) on solid Cu. Our work not only benchmarks quality of graphene grown on liquid copper for membrane applications but also provides fundamental insights into the origin of intrinsic defects in large-area graphene synthesized via bottom-up processes for membrane applications. 

Abstract The broad employment of water electrolysis for hydrogen (H 2 ) production is restricted by its large voltage requirement and low energy conversion efficiency because of the sluggish oxygen evolution reaction (OER). Herein, we report a strategy to replace OER with a thermodynamically more favorable reaction, the partial oxidation of formaldehyde to formate under alkaline conditions, using a Cu 3 Ag 7 electrocatalyst. Such a strategy not only produces more valuable anodic product than O 2 but also releases H 2 at the anode with a small voltage input. Density functional theory studies indicate the H 2 C(OH)O intermediate from formaldehyde hydration can be better stabilized on Cu 3 Ag 7 than on Cu or Ag, leading to a lower C-H cleavage barrier. A two-electrode electrolyzer employing an electrocatalyst of Cu 3 Ag 7 (+)||Ni 3 N/Ni(–) can produce H 2 at both anode and cathode simultaneously with an apparent 200% Faradaic efficiency, reaching a current density of 500 mA/cm 2 with a cell voltage of only 0.60 V. 

Incorporating atomically thin graphene into proton exchange membranes (PEMs)viascalable and facile processes presents the potential for advancing energy conversion and storage applications while mitigating persistent issues of undesired species crossover. 

ABSTRACT This study investigates the potential of few‐layered conductive graphene foams as 3D platforms for the electrical transdifferentiation of mesenchymal stem cells (MSCs) into Schwann cell (SC)‐like phenotypes for peripheral nerve injury (PNI) treatment. The 3D graphene foams (3D‐GF) are cytocompatible with MSCs and created a favorable microenvironment for the cells to attach, grow, proliferate, and transdifferentiate. We demonstrated that MSCs cultured within 3D‐GF can be transdifferentiated into SC‐like phenotypes using the synergistic effects of electrical stimulation and 3D porous and conductive structure. Our immunocytochemistry and gene expression analyses showed the expression of Schwann cell markers and enhanced secretion of growth factors, suggesting successful transdifferentiation of MSCs into SC‐like phenotypes upon electrical stimulation. Our degree of transdifferentiation results (∼90% by electrical) are comparable with conventionally used chemical stimuli‐based transdifferentiation protocols (∼85% by chemical). The secreted growth factors are also biologically active, showing enhanced neurite outgrowth in PC12TrkB cells compared to the control. Our transcriptomics results also showed that the electrical stimulation‐directed transdifferentiation mainly occurs through MAPK signaling pathway activation. These findings suggest that conductive 3D‐GF could serve as a promising platform for peripheral nerve regeneration applications, offering a novel approach to enhance the transdifferentiation and functional properties of MSCs.