Self‐Supported Nickel Single Atoms Overwhelming the Concomitant Nickel Nanoparticles Enable Efficient and Selective CO₂ Electroreduction

Abstract

Self‐supported metal/nitrogen‐doped carbon (M‐N‐C) catalysts with unitary single‐atom (SA) sites are highly desired to facilitate the electrocatalysis industrialization. Nevertheless, the concomitance of metal nanoparticles (NPs) enclosed by graphene layers is commonly inevitable and results in structure heterogeneity. Herein, an electronic structure modulation strategy of inactivating nickel (Ni) NPs to maximize Ni SAs for highly efficient and selective carbon dioxide reduction reaction (CO2RR) within a facilely prepared self‐supported Ni NPs/SAs‐containing catalyst is reported. The side effect of Ni NPs is effectively inhibited by finely tuning the encapsulating graphene layers thickness to block electrons penetration. The optimized catalyst exhibits a nearly 100% selectivity of CO production under moderate working potentials of −0.6– −0.8 V (vs reversible hydrogen electrode) and produces a partial current density of 341 mA cm−2 when directly used as a gas diffusion electrode for CO2RR. The authors’ discoveries provide fresh insights into the design and scalable preparation of self‐supported M‐N‐C catalysts with unitary single‐atom active sites for CO2RR aiming at industrialization.

Tunable Syngas Formation at Industrially Relevant Current Densities via CO2 Electroreduction and Hydrogen Evolution over Ni and Fe‐derived Catalysts obtained via One‐Step Pyrolysis of Polybenzoxazine Based Composites

“…[48] XPS also reveals that the surface composition depends on the used carbon precursor, with a drastic change in Ni 1 D 5 , where six times less Ni is present on the surface compared to the bulk (Table S1, Supporting Information), likely due to the embedment of Ni NPs in the carbon structures as revealed by TEM analysis, or a more heterogeneous distribution through the material. While [49,50] The Ni LMM Auger spectra corroborate these observations (Figure S15, Supporting Information), as the profiles for Ni 1 D 5 B 1 and Ni 1 D 5 CB 1 are similar, and characteristic of Ni(OH) 2 /NiO, while Ni 1 D 5 shows a different profile, attributable to the presence of NiOOH. [48] The N1s high-resolution spectra of These results confirm that the MO x NPs support CO formation via eCO 2 RR at higher current densities.…”

Modulating the Structure and Composition of Single‐Atom Electrocatalysts for CO2 reduction

“…Compared with the thinner‐walled catalyst, Ni@NCT/CFM(1000) with a thicker shell performed a FE(CO) of nearly 100%, while the H 2 partial current density dramatically decreased, manifesting that the side reaction of HER on Ni NPs was successfully suppressed. [ 110 ] Pan et al constructed a hierarchical structure containing mesoporous carbon nanotubes and graphene nanoribbon networks (GNR). The as‐obtained catalyst Fe─N/CNT@GNR‐2 achieved a FE(CO) of 98% at −0.76 V versus RHE in an H‐cell with CO 2 ‐saturated 0.1 m KHCO 3 .…”

“…Chen [157] Copyright 2016, American Chemical Society. b) The most stable structure of Cu-doped CeO 2 (110) with three O vacancies, on which CO 2 is activated. [139] Copyright 2018, American Chemical Society.…”

Interfacing Dense NiFe@N-Doped Carbon Nanotubes on a Ni Hollow Fiber as a High-Current-Density Gas-Penetrable Electrode for Selective CO2 Electroreduction

“…Recently, transition metal (TM)-based electrocatalysts (TM = Fe, Co, Ni, Cu, Zn, etc.) including N-doped carbon-coordinated TMs single atoms (TMs 1 /NC), encapsulated TMs (TMs@NC), and supported TM (TMs/NC) have been extensively investigated for the eCO 2 RR due to their high abundance and performance–price ratio. − Among them, TMs@NC, also known as chainmail catalysts, have shown high activity and durability in eCO 2 RR due to the synergistic effect of core TMs and carbon shells. − In this context, Zhuo and co-workers reported that a carbon nanotube-encapsulated Ni nanoparticle catalyst prepared by a one-step chemical vapor deposition (CVD) approach exhibits a high Faradaic efficiency (FE) of 90% for CO production at an applied potential of −0.77 V versus reversible hydrogen electrode (RHE). Xie and co-workers demonstrated that the F, N-codoped carbon-coated iron carbide nanoparticles also show exceptional performance toward the electroreduction of CO 2 to CO with a high FE of 97.7% and current density of 7.9 mA cm 2 at −0.7 V versus RHE.…”