Enhanced electrocatalysis performance of amorphous electrolytic carbon from CO2 for oxygen reduction by surface modification in molten salt

Electrochemical splitting of methane in melts: Producing and tuning high-value carbon materials with controllable morphology

Catalytic decomposition of methane offers a viable solution for producing pure hydrogen and nanocarbon without emitting carbon dioxide. However, conventional thermal catalytic processes and catalysts have limitations in terms of poor carbon quality and catalyst deactivation due to carbon deposition. The newly developed electrochemical splitting of methane (ESM) in molten salt has emerged as a promising alternative that allows for the separate production of hydrogen at the anode and carbon deposition at the cathode. In this study, hydrogen produced via ESM while generating nanocarbon with diverse structures through manipulations of the cathode material and kinetics. Carbon nanotubes grown on Ni cathode, possessing high specific surface area and abundant functional groups, displayed excellent adsorptive capacity for dye adsorption. The open hollow nanocarbon grown on the Ag cathode displayed good capacitance performance. ESM technology has immense potential to enhance the utilization value of carbon by-products and the commercial production of green hydrogen.

Bionic Preparation of CeO2-Encapsulated Nitrogen Self-Doped Biochars for Highly Efficient Oxygen Reduction

This study reports the superior performance of novel carbonaceous materials, CeO₂-encapsulated nitrogen-doped biochars [BC-Ce-X (X = 1 and 2)], for oxygen reduction reaction (ORR). The biomass precursor of this value-added biochar material was biomimetically prepared via a hydroponic operation in the Ce-enriched solution. The characterization results showed that CeO₂ with large amounts of oxygen vacancies was stably embedded in the N self-doped biochars during the pyrolytic processes. The measured specific surface areas of cerium-free biochar (BC sample), BC-Ce-1, and BC-Ce-2 were 79, 566, and 518 m²/g, respectively. The BC-Ce-X (X = 1 and 2) showed excellent ORR performances with onset potentials of ∼0.90-0.91 V, which outperformed the commercial 10 wt % Pt/C and BC. Compared with Pt/C, the BC-Ce-2 had better methanol tolerance and stability. Also, BC-Ce-2 displayed excellent electrochemical activity for Zn/air batteries. Controlled experiments and density functional theoretical calculations illustrated the synergistic effect between the pyri-N/C centers and CeO₂ with oxygen vacancies in ORR. The Lewis base sites, created by pyri-N and oxygen vacancies, greatly facilitated the chemisorption of O₂ molecules.