Exfoliated graphite with spinel oxide as an effective hybrid electrocatalyst for water splitting.

The aim of the conducted research was to develop hybrid nanostructures formed from MnCo2O4 and exfoliated graphite. Carbon added during the synthesis allowed for obtaining a well-distributed MnCo2O4 particle size with exposed active sites contributing to the increased electric conductivity. The influence of the weight ratios of carbon to a catalyst for hydrogen and oxygen evolution reactions was investigated. The new bifunctional catalysts for water splitting were tested in an alkaline medium with excellent electrochemical performance and very good working stability. The results for hybrid samples show better electrochemical performance compared to the pure MnCo2O4. The highest electrocatalytic activity was for sample MnCo2O4/EG (2/1), where the value of the overpotential was 1.66 V at 10 mA cm-2, and also for this sample a low value of Tafel slope (63 mV dec-1) was denoted.

Green algae and gelatine derived nitrogen rich carbon as an outstanding competitor to Pt loaded carbon catalysts.

The development of effective catalysts for the oxygen reduction reaction (ORR) is a significant challenge in energy conversion systems, e.g., Zn-air batteries. Herein, green-algae- and gelatine-derived porous, nitrogen-rich carbons were extensively investigated as electrode materials for electrochemical catalytic reactions. These carbon-based catalysts were designed and optimized to create a metal-free catalyst via templating, carbonization, and subsequent removal of the template. The additional incorporation of graphene improved electronic conductivity and enhanced the electrochemical catalytic reaction. Porous carbons with heteroatoms were used as effective platinum-free ORR electrocatalysts for energy conversion; the presence of nitrogen in the carbon provided more active sites for ORR. Our catalyst also displayed notable durability in a rechargeable Zn-air battery energy system. More importantly, the nitrogen-containing porous carbons were found to have comparable ORR performance in alkaline media to commercially available electrocatalysts. The manuscript demonstrates that nitrogen atom insertion is an appropriate approach when aiming to eliminate noble metals from the synthesis route. N-doped carbons are competitive materials compared to reference platinum-based catalysts.