Thin Carbon Layer Enveloped Cobalt-Iron Oxide Nanocages as High-Efficiency Sulfur Container for Li-S Batteries

• Key Words:ETHYLENE HYDROGENATION; COBALT OXIDE; ELECTROCATALYSTS; SURFACE; NANOSHEETS; VACANCIES; STABILITY; CATALYSTS; ENHANCE; TIO2
• Abstract:Electrocatalytic water splitting has received widespread attention. However, due to the slow reaction kinetics and complex electron transfer process, the oxygen evolution reaction (OER) occurring at the anode has become a bottleneck. Herein, the metal-defective Co3-xO4 was selected as the electron-acceptor carrier and Co3-xO4/NiO was synthesized by a simple two-step method. The results show that Co3-xO4/NiO has a low overpotential of 240 mV and 320 mV at 10 mA center dot cm(-2) and 100 mA center dot cm(-2), a low Tafel slope of 64 mV/dec, and the electrochemical surface area (ECSA) of Co3-xO4/NiO is as high as 1033.3 cm(2). Moreover, the decrease in activity after the 60 h stability testing is negligible. Combining experiments and theoretical calculations, the high activity and stability of Co3-xO4/NiO is attributed to the tunable electronic structure, and more electrons are transferred from NiO to Co3-xO4 which leads to the in-situ generation of more Ni3+ as active sites. The Co3-xO4/NiO with abundant of Ni3+ can effectively regulate the oxygen-containing intermediates (OH*, O* and OOH*) with appropriate binding energy, reduce Gibbs free energy change of rate-limiting step, and accelerate OER reaction kinetics. This work provides an efficient strategy to generate and stabilize Ni3+ active sites and confirms the key catalytic role of Ni3+ in the OER process.
• Volume:446
• Issue:
• Translation or Not:no