Ni electrodes with 3D-ordered surface structures for boosting bubble releasing toward high current density alkaline water splitting.

The performance of alkaline water electrolysis (AWE) at high current densities is limited by gas bubble generation on the surface of electrodes, which covers active sites and blocks mass transfer, resulting in lower AWE efficiency. Here, we utilize electro-etching to construct Ni electrodes with hydrophilic and aerophobic surfaces to improve the efficiency of AWE. Ni atoms on the Ni surface can be exfoliated orderly along the crystal planes by electro-etching, forming micro-nano-scale rough surfaces with multiple crystal planes exposed. The 3D-ordered surface structures increase the exposure of active sites and promote the removal of bubbles on the surface of the electrode during the AWE process. In addition, experimental results from high-speed camera reveal that rapidly released bubbles can improve the local circulation of electrolyte. Lastly, the accelerated durability test based on practical working condition demonstrates that the 3D-ordered surface structures are robust and durable during the AWE process.

Dynamic ginsenoside-sheltered nanocatalysts for safe ferroptosis-apoptosis combined therapy.

Chemodynamic therapy (CDT)-activated apoptosis is a potential anticancer strategy. However, CDT encounters a bottleneck in clinical translation due to its serious side effects and low efficacy. Here, we first reveal that surface engineering of ginsenoside Rg3 dramatically alters the organ distribution and tumor enrichment of systematically administered nanocatalysts using the orthotopic pancreatic tumor model while avoiding toxicity and increasing efficacy in vivo to address the key and universal toxicity problems encountered in nanomedicine. Compared with nanocatalysts alone, Rg3-sheltered dynamic nanocatalysts form hydrophilic nanoclusters, prolonging their circulation lifespan in the blood, protecting the internal nanocatalysts from leakage while allowing their specific release at the tumor site. Moreover, the nanoclusters provide a drug-loading platform for Rg3 so that more Rg3 reaches the tumor site to achieve obvious synergistic effect with nanocatalysts. Rg3-sheltered dynamic nanocatalysts can simultaneously activate ferroptosis and apoptosis to significantly improve anticancer efficacy. Systematic administration of ginsenoside Rg3-sheltered nanocatalysts inhibited 86.6% of tumor growth without toxicity and prolonged the survival time of mice. This study provides a promising approach of nanomedicine with high biosafety and a new outlook for catalytic ferroptosis-apoptosis combined antitumor therapies. STATEMENT OF SIGNIFICANCE: Chemodynamic therapy (CDT) has limited clinical efficacy in cancer. In this study, we developed Rg3-sheltered dynamic nanocatalysts, which could simultaneously activate ferroptosis based on CDT-activated apoptosis, and ultimately form a combined therapy of ferroptosis-apoptosis to kill tumors. Studies have shown that the nanocatalysts after Rg3 surface engineering dramatically alters the pharmacokinetics and organ distribution of the nanocatalysts after being systematically administered, resulting in avoiding the toxicity of the nanocatalysts. Nanocatalysts also act as a drug-loading platform, guiding more Rg3 into the tumor site. This study emphasizes that nanocatalysts after Rg3 surface engineering improve the safety and effectiveness of ferroptosis-apoptosis combined therapy, providing an effective idea for clinical practices.

N, P-Codoped Graphene Dots Supported on N-Doped 3D Graphene as Metal-Free Catalysts for Oxygen Reduction.

Nitrogen and phosphorus-codoped graphene dots supported on nitrogen-doped three-dimensional graphene (N, P-GDs/N-3DG) have been synthesized by a facile freeze-annealing process. On the surface of the 3D interconnected porous structure, the N, P-GDs are uniformly dispersed. The as-prepared N, P-GDs/N-3DG material served as a metal-free catalyst for oxygen reduction reaction (ORR) in an alkaline medium and evaluated by a rotating ring-disk electrode. The N, P-GDs/N-3DG catalyst exhibits excellent ORR activity, which is comparable to that of the commercial Pt/C catalyst. Furthermore, it exhibits a higher tolerance to methanol and better stability than the Pt/C. This enhanced electrochemical catalytic performance can be ascribed to the presence of abundant functional groups and edge defects. This study indicates that P-N bonded structures play a vital role as the active sites in ORR.