Electrochemical CO 2 reduction is a promising way to mitigate CO 2 emissions and close the anthropogenic carbon cycle. Among products from CO 2 RR, multicarbon chemicals, such as ethylene and ethanol with high energy density, are more valuable. However, the selectivity and reaction rate of C 2 production are unsatisfactory due to the sluggish thermodynamics and kinetics of C−C coupling. The electric field and thermal field have been studied and utilized to promote catalytic reactions, as they can regulate the thermodynamic and kinetic barriers of reactions. Either raising the potential or heating the electrolyte can enhance C−C coupling, but these come at the cost of increasing side reactions, such as the hydrogen evolution reaction. Here, we present a generic strategy to enhance the local electric field and temperature simultaneously and dramatically improve the electric−thermal synergy desired in electrocatalysis. A conformal coating of ∼5 nm of polytetrafluoroethylene significantly improves the catalytic ability of copper nanoneedles (∼7-fold electric field and ∼40 K temperature enhancement at the tips compared with bare copper nanoneedles experimentally), resulting in an improved C 2 Faradaic efficiency of over 86% at a partial current density of more than 250 mA cm −2 and a record-high C 2 turnover frequency of 11.5 ± 0.3 s −1 Cu site −1 . Combined with its low cost and scalability, the electric−thermal strategy for a state-of-the-art catalyst not only offers new insight into improving activity and selectivity of value-added C 2 products as we demonstrated but also inspires advances in efficiency and/or selectivity of other valuable electro-/photocatalysis such as hydrogen evolution, nitrogen reduction, and hydrogen peroxide electrosynthesis.
Combining transition metal oxide catalysts with conductive carbonaceous material is a feasible way to improve the conductivity. However, the electrocatalytic performance is usually not distinctly improved because the interfacial resistance between metal oxides and carbon is still large and thereby hinders the charge transport in catalysis. Herein, the conductive interface between poorly conductive NiO nanoparticles and semi-conductive carbon nitride (CN) is constructed. The NiO/CN exhibits much-enhanced oxygen evolution reaction (OER) performance than corresponding NiO and CN in electrolytes of KOH solution and phosphate buffer saline, which is also remarkably superior over NiO/C, commercial RuO 2 , and mostly reported NiO-based catalysts. X-ray photoelectron spectroscopy and extended X-ray absorption fine structure spectrum reveal that a metallic Ni-N bond is formed between NiO and CN. Density functional theory calculations suggest that NiO and CN linked by a Ni-N bond possess a low Gibbs energy for OER intermediate adsorptions, which not only improves the transfer of charge but also promotes the transmission of mass in OER. The metal-nitrogen bonded conductive and highly active interface pervasively exists between CN and other transition metal oxides including Co 3 O 4 , CuO, and Fe 2 O 3 , making it promising as an inexpensive catalyst for efficient water splitting.
Enhanced carbon dioxide reduction reaction (CO2RR) with suppressed HER was achieved on polytetrafluoroethylene (PTFE) coated Cu nanoneedles (CuNNs).
Converting CO2 into carbon‐based fuels is promising for relieving the greenhouse gas effect and the energy crisis. However, the selectivity and efficiency of current electrocatalysts for CO2 reductions are still not satisfactory. In this paper, the development of machine learning methods in screening CO2 reduction electrocatalysts over the recent years is reviewed. Through high‐throughput calculation of some key descriptors such as adsorption energies, d‐band center, and coordination number by well‐constructed machine learning models, the catalytic activity, optimal composition, active sites, and CO2 reduction reaction pathway over various possible materials can be predicted and understood. Machine learning is now realized as a fast and low‐cost method to effectively explore high performance electrocatalysts for CO2 reduction.
Electrocatalytic hydrogen evolution reaction (HER) in alkaline media is a promising electrochemical energy conversion strategy. Ruthenium (Ru) is an efficient catalyst with a desirable cost for HER, however, the sluggish H2O dissociation process, due to the low H2O adsorption on its surface, currently hampers the performances of this catalyst in alkaline HER. Herein, we demonstrate that the H2O adsorption improves significantly by the construction of Ru-O-Mo sites. We prepared Ru/MoO2 catalysts with Ru-O-Mo sites through a facile thermal treatment process and assessed the creation of Ru-O-Mo interfaces by transmission electron microscope (TEM) and extended X-ray absorption fine structure (EXAFS). By using Fourier-transform infrared spectroscopy (FTIR) and H2O adsorption tests, we proved Ru-O-Mo sites have tenfold stronger H2O adsorption ability than that of Ru catalyst. The catalysts with Ru-O-Mo sites exhibited a state-of-the-art overpotential of 16 mV at 10 mA cm -2 in 1 M KOH electrolyte, demonstrating a threefold reduction than the previous bests of Ru (59 mV) and commercial Pt (31 mV) catalysts. We proved the stability of these performances over 40 hours without decline. These results could open a new path for designing efficient and stable catalysts.
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