Zipeng Zeng,Aya Gomaa Abdelkader Mohamed,Xiang Zhang,Yaobing Wang
Although metal–N-doped carbons are promising electrocatalysts for CO 2 -to-CO conversion due to their high conversion efficiency and current density, their commercial application is still challenging due to their narrow potential/current range. In general, a wide potential/current electrocatalyst is in high demand for industrial CO 2 electrocatalysis. Controllable strategy to tune N configurations toward pyridinic-enriched metal–N x active sites is attractive. The synergetic effect of the ability of pyridinic N to capture Lewis acidic CO 2 and the characteristics of Ni–N active sites to inhibit the hydrogen evolution reaction (HER) can achieve a wide potential window, which has high practical value. Herein, the well-chosen precursors resulting in a pyridinic-enriched Ni–N x site can selectively catalyze CO 2 toward CO generation in aqueous media with a high Faradaic efficiency (FE) of 100% with an overpotential of 680 mV. Continuous CO FE > 90% was recorded under a wide range of potentials without decay. Motivated by its practical characteristics in CO 2 electrocatalysts, a Zn–CO 2 battery is assembled achieving a CO 2 –CO conversion efficiency of more than 90% in a wide discharge current window. Therefore, the results highlight that pyridinic-enriched Ni–N x holds great promise as simultaneous CO-selective electrocatalyst by suitably tuning M–N configurations as new perspective strategy.
Shuai Liu,Mengmeng Jin,Jiaqiang Sun,Yongji Qin,Sanshuang Gao,Yu Chen,Shusheng Zhang,Jun Luo,Xijun Liu
Electrocatalytic CO 2 reduction reaction (CRR), powered by renewable energy sources, is a promising route to address energy and environmental issues. Herein, we fabricate single atomic Fe sites anchored on B and N co-doped carbon (Fe-SA/BNC), which showed excellent CRR activity, achieving a highest Faradaic efficiency of ∼ 94% at −0.7 V versus reversible hydrogen electrode. The performance is much better than that of the B-free sample. Furthermore, an outstanding current density of ∼ 130 mA cm −2 , as well as ∼ 99% Faradaic efficiency, has been achieved using the membrane electrode assembly (MEA). Details of density functional theory (DFT) calculations revealed that the introduction of B was beneficial for the desorption of *CO. The Zn-CO 2 battery was then assembled, which reached a high peak power density of 1.18 mW cm −2 at a current density of 4 mA cm −2 , as well as showing remarkable stability for CO production.
The selective electrochemical reduction of CO 2 to CO is a promising solution for the design of carbon-neutral, sustainable processes. Achieving a highly selective single reduction product is still challenging because of the energetically favorable competing hydrogen evolution reaction. We report the fabrication of N-doped sponge-like porous graphitic carbon structures embedded with Fe nanoparticles (Fe@NPC) via the pre-modification of a metal-organic framework (IRMOF-3(Zn)) with carboxyferrocene, followed by pyrolysis . The as-prepared Fe@NPC exhibited a 96.4% CO Faradaic efficiency at –0.5 V RHE and good stability. The exceptional CO 2 reduction performance is attributed to the unique structure of the composite catalyst, which provides abundant hierarchical pores that increase CO 2 adsorption and mass transfer, and active Fe sites that synergistically accelerate the kinetics of CO generation. The in situ attenuated total reflectance-Fourier transform infrared analysis provided proof of the improved ability of Fe@NPC to accumulate the crucial intermediate *COOH compared with other pyrolyzed porous carbons. Fe@NPC was used in a Zn-CO 2 battery that delivered a maximum power density of 3.0 mW cm –2 , evidencing its potential for application in energy-converting devices.
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