Search

Designing hybrid transition metal compounds with optimized electronic structure and firmly dispersing them on a matrix to avoid aggregation and shedding is of great significance for achieving high electrocatalytic performances. Herein, an adsorption-complexation-calcination strategy based on channel confining effect is explored to obtain CoN-CoOx hybrid nanoparticles uniformly dispersed in mesoporous carbon. The CoN-CoOx/C composite exhibits excellent electrocatalytic behavior for oxygen reduction reaction (ORR). The half-wave potential and durability are comparable or superior to those of Pt/C. When applying as cathode catalyst for a primary zinc-air battery, the open-circuit voltage and peak power density reach up to 1.394 V and 109.8 mW·cm−2, respectively. A high gravimetric energy density of 950.3 Wh·kgZn−1 is delivered at 10 mA·cm−2 with good rate capability and stability. Density functional theory (DFT) calculation demonstrates the favorable ORR intermediate adsorbability and metallic characteristics of CoN grains with oxide hybridization to optimize the electronic structure. This work provides a facile adjustable approach for obtaining highly dispersed nanoparticles with controllable hybrid composition on a substrate, which is important for future design and optimization of high-performance electrocatalysts. [ABSTRACT FROM AUTHOR]

Searching for efficient non‐noble metal electrocatalyst for oxygen reduction reaction (ORR) has become a hot topic in electrochemical field. Herein, duck blood containing heme (a type of ferriporphyrin) is carbonized and activated to obtain Fe, N doped carbon. The activated carbonized blood (a‐CB) exhibits an extremely high specific surface area of 2655 m2 g–1. Then, Co3O4 nanoparticles are loaded on the efficient substrate via hydrothermal method. The as obtained Co3O4/a‐CB composite exhibits good catalytic performance for ORR. The onset and half‐wave potentials are 0.95 and 0.77 V vs. RHE, respectively. These values are comparable to those of commercial Pt/C (20 wt.‐%) catalyst. What's more, Co3O4/a‐CB shows better durability and methanol tolerance than commercial Pt/C, making it a promising electrocatalyst for ORR. Compared to artificial porous heteroatom doped carbon materials, this work seeks raw materials from natural biomass waste to obtain efficient carbon substrate with both high porosity and Fe, N self‐doping feature for catalyst applications. [ABSTRACT FROM AUTHOR]

• A coadsorption-pyrolysis method was used to prepare CoO/Co-N-C on mesoporous carbon. • Ultrafine CoO and Co-N-C lamellae were the electrocatalytically active species. • Mesoporous carbon as the substrate enabled efficient mass and charge transport. • Co/Co-N-C/MC had excellent activity and stability for the oxygen reduction reaction. • A zinc-air battery with high peak power density and specific capacity was fabricated. Designing and synthesizing high-efficiency non-precious metal electrocatalysts are of great significance for electrochemical reduction of oxygen. A simple coadsorption-pyrolysis method is developed to synthesize ultra-small CoO nanoparticles and Co-N-C lamellae supported on ordered mesoporous carbon (MC). The optimized CoO/Co-N-C/MC electrocatalyst has good catalytic activity for oxygen reduction reaction (ORR) with a half-wave potential of 0.78 V vs. RHE and a limiting current density of 5.01 mA cm−2. The high ORR activity, together with the superior stability compared with Pt/C, make it a good choice as cathode catalyst in zinc-air batteries (ZABs). The as-assembled ZAB has a high open circuit voltage of 1.397 V and a specific capacity of 842 mAh g Zn −1 at 10 mA cm−2. The good performance is attributed to the abundant ultrafine CoO particles and Co-N-C lamellae as catalytic active sites, as well as the mesoporous substrate for efficient mass/charge transport. [Display omitted] [ABSTRACT FROM AUTHOR]