Resveratrol Inhibits Zinc Deficiency-Induced Mitophagy and Exerts Cardiac Cytoprotective Effects.

Resveratrol (Res) possesses various beneficial effects, including cardioprotective, anti-inflammatory, anti-aging, and antioxidant properties. However, the precise mechanism underlying these effects remains unclear. Here we investigated the protective effects of resveratrol on cardiomyocytes, focusing on the role of Zn2+ and mitophagy. Using the MTT/lactate dehydrogenase assay, we found that addition of a zinc chelator TPEN for 4 h induced mitophagy and resulted in a significant reduction in cell viability, increased cytotoxicity, and apoptosis in H9c2 cells. Notably, resveratrol effectively mitigated these detrimental effects caused by TPEN. Similarly, Res inhibited the TPEN-induced expression of mitophagy-associated proteins, namely P62, LC3, NIX, TOM20, PINK1, and Parkin. The inhibitory action of resveratrol on mitophagy was abrogated by the mitophagy inhibitor 3-MA. Additionally, we discovered that silencing of the Mfn2 gene could reverse the inhibitory effects of resveratrol on mitophagy via the AMPK-Mfn2 axis, thereby preventing the opening of the mitochondrial permeability transition pore (mPTP). Collectively, our data suggest that Res can safeguard mitochondria protection by impeding mitophagy and averting mPTP opening through the AMPK-Mfn2 axis in myocardial cells.

Zinc Overload Induces Damage to H9c2 Cardiomyocyte Through Mitochondrial Dysfunction and ROS-Mediated Mitophagy.

Zinc homeostasis is essential for maintaining redox balance, cell proliferation, and apoptosis. However, excessive zinc exposure is toxic and leads to mitochondrial dysfunction. In this study, we established a zinc overload model by treating rat cardiomyocyte H9c2 cells with Zn2+ at different concentrations. Our results showed that zinc overload increased LDH and reactive oxygen species (ROS) levels, leading to cell death, mitochondrial membrane potential decrease and impaired mitochondrial function and dynamics. Furthermore, zinc overload activated the PINK1/Parkin signaling pathway and induced mitochondrial autophagy via ROS, while NAC inhibited mitophagy and weakened the activation of PINK1/Parkin pathway, thereby preserving mitochondrial biogenesis. In addition, our data also showed that Mfn2 deletion increased ROS production and exacerbated cytotoxicity induced by zinc overload. Our results therefore suggest that Zn2+-induced ROS generation causes mitochondrial autophagy and mitochondrial dysfunction, damaging H9c2 cardiomyocytes. Additionally, Mfn2 may play a key role in zinc ion-mediated endoplasmic reticulum and mitochondrial interactions. Our results provide a new perspective on zinc-induced toxicology.

Understanding Alkaline Hydrogen Oxidation Reaction on PdNiRuIrRh High-Entropy-Alloy by Machine Learning Potential.

High-entropy alloy (HEA) catalysts have been widely studied in electrocatalysis. However, identifying atomic structure of HEA with complex atomic arrangement is challenging, which seriously hinders the fundamental understanding of catalytic mechanism. Here, we report a HEA-PdNiRuIrRh catalyst with remarkable mass activity of 3.25 mA µg-1 for alkaline hydrogen oxidation reaction (HOR), which is 8-fold enhancement compared to that of commercial Pt/C. Through machine learning potential-based Monte Carlo simulation, we reveal that the dominant Pd-Pd-Ni/Pd-Pd-Pd bonding environments and Ni/Ru oxophilic sites on HEA surface are beneficial to the optimized adsorption/desorption of *H and enhanced *OH adsorption, contributing to the excellent HOR activity and stability. This work provides significant insights into atomic structure and catalytic mechanism for HEA and offers novel prospects for developing advanced HOR electrocatalysts.

Ce-induced regulation of electron density enhanced the catalytic activity of Co-Mn oxides for water oxidation.

The incorporation of Ce into Co-Mn oxides induced the charge redistribution of Co and Mn via electronic coupling, which facilitated the Co3+/Co4+ transition. Thus, the overpotential at 10 mA cm-2 was reduced significantly by 73 mV for the oxygen evolution reaction after Ce doping.

Intrinsic Carbon Defects for the Electrosynthesis of H2O2.

Carbon materials have manifested promising potential in electrochemical reduction of O2 to H2O2. The oxygen functional groups have been identified as the catalytic sites. However, the intrinsic carbon defects abundant in carbon materials have often been neglected. Herein, a three-dimensional carbon framework with abundant intrinsic defects and oxygen functional groups (the oxygen content and chemical states of oxygen are comparable to those of commercial carbon black) was introduced and exhibited outstanding catalytic activity and selectivity toward H2O2 electrosynthesis. Through a combination of in situ Raman spectroscopy and density functional theory calculations, the intrinsic carbon defects, such as zigzag edge and zigzag pentagon sites with optimal binding energy for OOH, were also determined to be active sites. It was further revealed that intrinsic carbon defects with large negative charge density and asymmetric spin density may have high activity toward H2O2 production.

Top-Open Hollow Nanocubes of Ni-Doped Cu Oxides on Ni Foam: Scalable Oxygen Evolution Electrode via Galvanic Displacement and Face-Selective Etching.

Self-standing and cost-effective electrodes for high-performance oxygen evolution reaction (OER) are vital for emerging energy storage and conversion technologies. We report a scalable binder-free OER electrode with open hollow nanocubes of Ni-doped CuOx on Ni foam (hNC/NF) through spontaneous galvanic displacement followed by simple electrochemical oxidation. Face-selective etching for the unique structure of hollow nanocubes with large open ends is achieved by utilizing the different accessibility of the top and side faces of cubes to solution species, more specifically the depletion of reactants between the densely supported nanocubes. Besides, the in situ deposition on Ni foam allows spontaneous Ni doping, which, as revealed by DFT calculations, fortunately strengthens the adsorption of oxygenated intermediates and therefore could optimize the free energy path of OER on Cu oxides. Benefiting further from the high accessible surface area of the unique open hollow architecture, the hNC/NF exhibits an outstanding OER activity with a small overpotential (η = 305 mV at 10 mA cm-2) as well as excellent stability without significant decay after 120 h operation. To our knowledge, this should represent the best OER performance of Cu-based electrocatalysts and is competitive with those based on Fe-group metals. Besides, the hNC/NF-based water electrolyzer delivers a performance of 1.50 V cell voltage at 10 mA cm-2, offering great promise for practical application.

Spontaneous self-intercalation of copper atoms into transition metal dichalcogenides.

Intercalated transition metal dichalcogenides (TMDs) have attracted substantial interest due to their exciting electronic properties. Here, we report a unique approach where copper (Cu) atoms from bulk Cu solid intercalate spontaneously into van der Waals (vdW) gaps of group IV and V layered TMDs at room temperature and atmospheric pressure. This distinctive phenomenon is used to develop a strategy to synthesize Cu species-intercalated layered TMD compounds. A series of Cu-intercalated 2H-NbS2 compounds were obtained with homogeneous distribution of Cu intercalates in the form of monovalent Cu (I), occupying the tetrahedral sites coordinated by S atoms within the interlayer space of NbS2. The Fermi level of NbS2 shifts up because of the intercalation of Cu, resulting in the improvement of electrical conductivity in the z-direction. On the other hand, intercalation of Cu into vdW gaps of NbS2 systematically suppresses the superconducting transition temperature (T c) and superconducting volume fraction.

Discrepant roles of adsorbed OH* species on IrWOx for boosting alkaline hydrogen electrocatalysis.

Improving the slow kinetics of alkaline hydrogen electrode reactions, involving hydrogen oxidation and evolution reactions (HOR/HER) is highly desirable for accelerating the commercialization of alkaline exchange membrane-based fuel cells (AEMFCs) and water electrolyzers (AEMWEs). However, fundamental understanding of the mechanism for HOR/HER catalysis under alkaline media is still debatable. Here we develop an amorphous tungsten oxide clusters modified iridium-tungsten nanocrystallines (IrWOx) which exhibited by far the highest exchange current density and mass activity, about three times higher than the commercial Pt/C toward alkaline HOR/HER. Density functional theory (DFT) calculations reveal the WOx clusters act as a pivotal role to boost reversible hydrogen electrode reactions in alkaline condition but via different mechanisms, which are, hydrogen binding energy (HBE) mechanism for HOR and bi-functional mechanism for HER. This work is expected to promote our fundamental understanding about the alkaline HOR/HER catalysis and provide a new avenue for rational design of highly efficient electrocatalysts toward HOR/HER under alkaline electrolytes.

Self-Powered and Highly Efficient Production of H2O2 through a Zn-Air Battery with Oxygenated Carbon Electrocatalyst.

Industrially producing H2O2 consumes lots of energy and generates byproducts. For the first time, we demonstrate the non-energy-consuming, self-powered production of H2O2 based on a Zn-air battery with oxygenated carbon electrocatalyst. The battery with power density of 360 W mgeo-2 at a operating voltage of 0.8 V exhibited high H2O2 production rate of 5.93 mol mgeo-2 h-1. By tuning the ratio of the oxygen-containg groups, the origin of the high activity was investigated. Combining the DFT calculations, we found that C-O-C and -CHO contribute more to the H2O2 production compared to other functional groups.