Cu₂O–Cu Hybrid Foams as High-Performance Electrocatalysts for Oxygen Evolution Reaction in Alkaline Media

Here 3D Cu₂O–Cu hybrid foams are developed as high-performance electrocatalysts for OER in alkaline solution. The hybrid foams are composed of Cu₂O–Cu dendrites with high surface area and high-speed electronic transmission networks, and they can provide fast transportation and short diffusion path for electrolyte and evolved O₂ bubbles. As the special surface and structure effects, the Cu₂O–Cu hybrid foams exhibit low onset overpotential of ∼250 mV, small Tafel slope of 67.52 mV dec^–1, and high durability over 50 h at a current density of 10 mA cm^–2 for OER in alkaline solution. The results of this study may be particularly beneficial for the development of a type of hybrid porous foam electrocatalysts for the electrochemical process in which at least one gas-phase is involved, such as H₂ or O₂ evolution reaction and O₂ or CO₂ electroreduction reaction

Pt-like Hydrogen Evolution Electrocatalysis on PANI/CoP Hybrid Nanowires by Weakening the Shackles of Hydrogen Ions on the Surfaces of Catalysts

The search for high active, stable, and cost-efficient hydrogen evolution reaction (HER) electrocatalysts for water electrolysis has attracted great interest. The coordinated water molecules in the hydronium ions will obviously reduce the positive charge density of H⁺ and hamper the ability of H⁺ to receive electrons from the cathode, leading to large overpotential of HER on nonprecious metal catalysts. Here we realize Pt-like hydrogen evolution electrocatalysis on polyaniline (PANI) nanodots (NDs)-decorated CoP hybrid nanowires (HNWs) supported on carbon fibers (CFs) (PANI/CoP HNWs-CFs) as PANI can effectively capture H⁺ from hydronium ions to form protonated amine groups that have higher positive charge density than those of hydronium ions and can be electro-reduced easily. The PANI/CoP HNWs-CFs as low-cost electrocatalysts show excellent catalytic performance toward HER in acidic solution, such as super high catalytic activity, small Tafel slope, and superior stability

Asymmetric Paper Supercapacitor Based on Amorphous Porous Mn₃O₄ Negative Electrode and Ni(OH)₂ Positive Electrode: A Novel and High-Performance Flexible Electrochemical Energy Storage Device

Here we synthesize novel asymmetric all-solid-state paper supercapacitors (APSCs) based on amorphous porous Mn₃O₄ grown on conducting paper (NGP) (Mn₃O₄/NGP) negative electrode and Ni­(OH)₂ grown on NGP (Ni­(OH)₂/NGP) as positive electrode, and they have attracted intensive research interest owing to their outstanding properties such as being flexible, ultrathin, and lightweight. The fabricated APSCs exhibit a high areal <i>C</i>_sp of 3.05 F/cm³ and superior cycling stability. The novel asymmetric APSCs also exhibit high energy density of 0.35 mW h/cm³, high power density of 32.5 mW/cm³, and superior cycling performance (<17% capacitance loss after 12 000 cycles at a high scan rate of 100 mV/s). This work shows the first example of amorphous porous metal oxide/NGP electrodes for the asymmetric APSCs, and these systems hold great potential for future flexible electronic devices

Design of Pd/PANI/Pd Sandwich-Structured Nanotube Array Catalysts with Special Shape Effects and Synergistic Effects for Ethanol Electrooxidation

Low cost, high activity, and long-term durability are the main requirements for commercializing fuel cell electrocatalysts. Despite tremendous efforts, developing non-Pt anode electrocatalysts with high activity and long-term durability at low cost remains a significant technical challenge. Here we report a new type of hybrid Pd/PANI/Pd sandwich-structured nanotube array (SNTA) to exploit shape effects and synergistic effects of Pd-PANI composites for the oxidation of small organic molecules for direct alcohol fuel cells. These synthesized Pd/PANI/Pd SNTAs exhibit significantly improved electrocatalytic activity and durability compared with Pd NTAs and commercial Pd/C catalysts. The unique SNTAs provide fast transport and short diffusion paths for electroactive species and high utilization rate of catalysts. Besides the merits of nanotube arrays, the improved electrocatalytic activity and durability are especially attributed to the special Pd/PANI/Pd sandwich-like nanostructures, which results in electron delocalization between Pd d orbitals and PANI π-conjugated ligands and in electron transfer from Pd to PANI