CoV₂O₆–V₂O₅ Coupled with Porous N‑Doped Reduced Graphene Oxide Composite as a Highly Efficient Electrocatalyst for Oxygen Evolution

Electrocatalysts with high intrinsic activity for the oxygen evolution reaction (OER) are greatly desired for sustainable oxygen-based electrochemical energy conversion. In this work, the bimetallic oxide composite consisting of CoV₂O₆ and V₂O₅ anchoring on nitrogen-doped reduced graphene oxide (CoV₂O₆–V₂O₅/NRGO-1) was synthesized directly by carbonization of the polyoxometalates, ethylenediamine, and graphene oxide precursors. CoV₂O₆–V₂O₅/NRGO-1 used as an electrocatalyst exhibits an ultralow overpotential of 239 mV vs RHE at the current density of 10 mA cm^–2 and excellent stability in 1 M KOH. Surprisingly, it has high intrinsic activity with the turnover frequency of 1.80 s^–1 at the overpotential of 300 mV, which is the highest among the electrocatalysts reported to date. Theoretical calculation proves that the outstanding electrocatalytic performance is attributed to synergistic effects, in which CoV₂O₆ acts as active sites while the hydrogen bond between V₂O₅ and intermediate HOO* of the OER greatly decreases the composite adsorption energy, thus reducing the overpotential. Most importantly, the results demonstrate for the first time that intermolecular hydrogen bonding plays a key role in improving electrocatalytic properties for the OER, which reveals a new method of designing novel OER electrocatalysts

Electronic Tuning of Active Sites in Bifunctional Covalent Organic Frameworks for Photoassisted CO₂ Electrocatalytic Full Reaction

Realizing simultaneously energy-efficiency improvement and green economic implementation remains a daunting challenge in addressing the low-efficiency issues of CO2 electroreduction to meet the sustainable development strategy. Here, we propose a series of porphyrin-based COFs (TTCOF-M, M = Co, Ni, and Cu) as model catalysts to study the hybrid CO2 electrocatalytic full reaction for the first time, during which the catalysts can simultaneously accomplish photoassisted CO2 electroreduction and 4-nitrophenol (4-NP) mineralization. As model catalysts, the effects of various parameters have been intensively studied from typical tandem electro-reactions to extended photoassisted ones. Specifically, TTCOF-Co can achieve the cathodic reduction efficiency increasing from 90 to 96% (−0.7 V) after illumination and simultaneously 5 times shortened reaction time with a 4-NP degradation efficiency of ∼99%. Notably, the 4-NP mineralization rate is calculated to be ∼93.51% with ∼30.27 mmol/g/h CO2 production rate, and a rarely investigated mechanism relating to the 4-NP electro-degradation has been intensively studied