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Electrocatalysts during ethanol oxidation still suffer from poor CO2 selectivity and are easily poisoned by CO intermediates at low overpotentials, causing great challenges for commercial viability of direct ethanol fuel cells. Herein, we report the synthesis of excavated RhNi alloy nanobranches constructed from ultrathin nanosheets with high-energy {110} facets and a large specific surface area (50.0 m2 g−1). These unique RhNi nanobranches achieve a CO2 selectivity of as high as 16.0% toward the EOR in alkaline solution, far exceeding the reported value of most Pd, Pt or Rh-based electrocatalysts in alkaline solution to date. More strikingly, the excavated RhNi nanobranches show outstanding CO-poisoning tolerance ability, resulting in a high CO2 selectivity at low potentials. Both CO stripping and in situ FTIR spectra of the EOR and CO oxidation analyses reveal that the alloying of Ni into Rh endows the nanobranches with high CO anti-poisoning ability, and thus great CO2 selectivity at low potentials. [ABSTRACT FROM AUTHOR]

Electrochemical reduction of CO2 has received much attention because of its potential in converting atmospheric CO2 into commodity products. One of the key challenges in electrochemical CO2 reduction is the competing hydrogen evolution reaction (HER) at reduction electrode potentials. In this work, we used a hybrid material composed of pyrolyzed zeolitic imidazolate frameworks (ZIFs) and multi-walled carbon nanotubes (MWCNTs) to selectively catalyze electrochemical reduction of CO2 to CO in aqueous solution with close to 100% faradaic efficiency and a current density up to 7.7 mA cm−2 at an overpotential of 740 mV. The MWCNT support is crucial to achieving superior selectivity, thanks to enhanced electron transport on the MWCNT network and expedited CO2 transport in the mesoporous structure constructed by the MWCNTs. Moreover, doping Fe into the hybrid further reduces the overpotential of CO2 reduction to 440 mV with a current density of 2 mA cm−2 and a CO faradaic efficiency of 97%. This work highlights the importance of optimizing electron and mass transport in turning moderate catalysts into superior ones with high activity and selectivity for CO2 reduction. [ABSTRACT FROM AUTHOR]