Enhancing H2O2 Electrosynthesis at Industrial-Relevant Current in Acidic Media on Diatomic Cobalt Sites.

Electrocatalytic synthesis of hydrogen peroxide (H2O2) in acidic media is an efficient and eco-friendly approach to produce inherently stable H2O2, but limited by the lack of selective and stable catalysts under industrial-relevant current densities. Herein, we report a diatomic cobalt catalyst for two-electron oxygen reduction to efficiently produce H2O2 at 50-400 mA cm-2 in acid. Electrode kinetics study shows a >95% selectivity for two-electron oxygen reduction on the diatomic cobalt sites. In a flow cell device, a record-high production rate of 11.72 mol gcat-1 h-1 and exceptional long-term stability (100 h) are realized under high current densities. In situ spectroscopic studies and theoretical calculations reveal that introducing a second metal into the coordination sphere of the cobalt site can optimize the binding strength of key H2O2 intermediates due to the downshifted d-band center of cobalt. We also demonstrate the feasibility of processing municipal plastic wastes through decentralized H2O2 production.

Wharton's jelly stem cells delivered via a curcumin-loaded nanofibrous wound dressings improved diabetic wound healing via upregulating VEGF and IGF genes: An in vitro and in vivo study.

Diabetic wounds pose an enduring clinical hurdle, marked by delayed recovery, persistent inflammation, and an elevated susceptibility to infections. Conventional treatment approaches often fall short of delivering optimal outcomes, prompting the exploration of innovative methods to enhance the healing process. Electrospun wound dressings offer superior healing, controlled drug release, enhanced cell proliferation, biocompatibility, high surface area, and antimicrobial properties. In the current study, polycaprolactone/gelatin-based nanofibrous wound dressings were developed for the delivery of Wharton's jelly stem cells and curcumin into the diabetic wounds bed. Curcumin was loaded into the polycaprolactone/gelatin solution and electrospun to produce curcumin-loaded scaffolds. In vitro experiments including scanning electron microscopy, cell viability assay, release assay, hemocompatibility assay, cell proliferation assay, and antibacterial assay were utilized to characterize the delivery system. Then, curcumin-loaded scaffolds were seeded with 30,000 Wharton's jelly stem cells and implanted into a rat model of diabetic wounds. Study showed that the scaffolds containing both Wharton's jelly stem cells and curcumin significantly improved diabetic wound closure (86.32 3.88% at the end of 14th day), augmented collagen deposition, and improved epithelial tissue formation. Gene expression studies showed that VEGF and IGF genes were significantly upregulated by the co-delivery system. Our developed system may have augmented diabetic wound healing via upregulating pro-healing genes.

Atomically dispersed Iridium on Mo2C as an efficient and stable alkaline hydrogen oxidation reaction catalyst.

Hydroxide exchange membrane fuel cells (HEMFCs) have the advantages of using cost-effective materials, but hindered by the sluggish anodic hydrogen oxidation reaction (HOR) kinetics. Here, we report an atomically dispersed Ir on Mo2C nanoparticles supported on carbon (IrSA-Mo2C/C) as highly active and stable HOR catalysts. The specific exchange current density of IrSA-Mo2C/C is 4.1 mA cm-2ECSA, which is 10 times that of Ir/C. Negligible decay is observed after 30,000-cycle accelerated stability test. Theoretical calculations suggest the high HOR activity is attributed to the unique Mo2C substrate, which makes the Ir sites with optimized H binding and also provides enhanced OH binding sites. By using a low loading (0.05 mgIr cm-2) of IrSA-Mo2C/C as anode, the fabricated HEMFC can deliver a high peak power density of 1.64 W cm-2. This work illustrates that atomically dispersed precious metal on carbides may be a promising strategy for high performance HEMFCs.

Tuning the apparent hydrogen binding energy to achieve high-performance Ni-based hydrogen oxidation reaction catalyst.

High-performance platinum-group-metal-free alkaline hydrogen oxidation reaction catalysts are essential for the hydroxide exchange membrane fuel cells, which generally require high Pt loadings on the anode. Herein, we report a highly active hydrogen oxidation reaction catalyst, NiCuCr, indicated by the hydroxide exchange membrane fuel cell with a high peak power density of 577 mW cm-2 (18 times as high as the Ni/C anode) and a stability of more than 150 h (a degradation rate slower by 7 times than the Ni/C anode). The spectroscopies demonstrate that the alloy effect from Cu weakens the hydrogen binding, and the surface Cr2O3 species enhance the interfacial water binding. Both effects bring an optimized apparent hydrogen binding energy and thus lead to the high hydrogen oxidation reaction performance of NiCuCr. These results suggest that the apparent hydrogen binding energy determines the hydrogen oxidation reaction performance and that its tuning is beneficial toward high electrocatalytic performance.