Hosting atomically dispersed nitrogen-coordinated iron sites (Fe–N4) on graphene offers unique opportunities for driving electrochemical CO2 reduction reaction (CO2RR) to CO. However, the strong adsorption of *CO on the Fe–N4 site embedded in intact graphene limits current density due to slow CO desorption process. Herein, we report how the manipulation of pore edges on graphene alters the local electronic structure of isolated Fe–N4 sites and improves their intrinsic reactivity for prompting CO generation. We demonstrate that constructing holes on graphene basal plane to support Fe–N4 can significantly enhance its CO2RR compared to the pore-deficient graphene-supported counterpart, exhibiting a CO Faradaic efficiency of 94% and a turnover frequency of 1630 h–1 at 0.58 V vs RHE. Mechanistic studies reveal that the incorporation of pore edges results in the downshifting of the d-band center of Fe sites, which weakens the strength of the Fe–C bond when the *CO intermediate adsorbs on edge-hosted Fe–N4, thus boosting the CO desorption and evolution rates. These findings suggest that engineering local support structure renders a way to design high-performance single-atom catalysts.

Atomically dispersed metal and nitrogen co-doped carbon (M-N/C) catalysts hold great promise for electrochemical CO2 conversion. However, there is a lack of cost-effective synthesis approaches to meet the goal of economic mass production of single-atom M-N/C with desirable carbon support architecture for efficient CO2 reduction. Herein, we report facile transformation of commercial carbon nanotube (CNT) into isolated Fe–N4 sites anchored on carbon nanotube and graphene nanoribbon (GNR) networks (Fe-N/CNT@GNR). The oxidization-induced partial unzipping of CNT results in the generation of GNR nanolayers attached to the remaining fibrous CNT frameworks, which reticulates a hierarchically mesoporous complex and thus enables a high electrochemical active surface area and smooth mass transport. The Fe residues originating from CNT growth seeds serve as Fe sources to form isolated Fe–N4 moieties located at the CNT and GNR basal plane and edges with high intrinsic capability of activating CO2 and suppressing hydrogen evolution. The Fe-N/CNT@GNR delivers a stable CO Faradaic efficiency of 96% with a partial current density of 22.6 mA cm–2 at a low overpotential of 650 mV, making it one of the most active M-N/C catalysts reported. This work presents an effective strategy to fabricate advanced atomistic catalysts and highlights the key roles of support architecture in single-atom electrocatalysis.

Electrochemical CO2 reduction reaction (ECO2RR) is a potentially promising way of producing sustainable energy by converting CO2 into fuels or useful chemicals using alternative power sources such as solar and wind. However, finding cheap and abundant materials with a high catalytic activity for CO2 reduction is critical for future larger-scale applications of ECO2RR. Herein, we used petroleum coke (PC), an industrial waste, as the carbon source for preparing highly efficient ECO2RR catalysts. By doping nickel and nitrogen into oxidized PC (Ni–N-PC), an ∼97% Faradaic efficiency of CO production has been achieved with a current density of ∼18 mA/cm2 at −0.8 V versus the reversible hydrogen electrode. By further doping iron into the Ni–N-PC catalyst (forming Fe/Ni–N-PC), a 90% Faradaic efficiency of CO and a 20 mA/cm2 CO partial current density were achieved. The ECO2RR performance of the above PC-based catalysts was comparable to that of traditional graphite-based catalysts, but the former is an industrial waste and costs little. Findings from this work provide insight into transfer of industrial waste into a carbon precursor under similar treatment to synthesize efficient ECO2RR catalysts.

Heavy metal contamination has caused serious impacts on the environments and risks towards human health, promoting intensive R&D efforts for removal of heavy metals from their primary sources (industrial and...

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The structurally and chemically engineered graphenes have promoted the increase of the electrosorption capacity from 1.85 to ∼150 mg g−1.

3D graphene with rich surface-pores was demonstrated an excellent anode material for Li-ion batteries.

High areal capacitance for a practical supercapacitor electrode requires both large mass loading and high utilization efficiency of electroactive materials, which presents a great challenge. Herein, we demonstrated the unprecedented synthesis of superstructured NiMoO 4 @CoMoO 4 core-shell nanofiber arrays (NFAs) on a Mo-transition-layer-modified nickel foam (NF) current collector as a new material, achieving the synergistic combination of highly conductive CoMoO 4 and electrochemical active NiMoO 4 . Moreover, this superstructured material exhibited a large gravimetric capacitance of 1,282.2 F/g in 2 M KOH with a mass loading of 7.8 mg/cm 2 , leading to an ultrahigh areal capacitance of 10.0 F/cm 2 that is larger than any reported values of CoMoO 4 and NiMoO 4 electrodes. This work provides a strategic insight for rational design of electrodes with high areal capacitances for supercapacitors.