Room-Temperature Synthesis of Single Iron Site by Electrofiltration for Photoreduction of CO₂ into Tunable Syngas

Abstract

Developing a convenient and effective method to prepare single-atom catalysts at mild synthetic conditions remains a challenging task. Herein, a voltage-gauged electrofiltration method was demonstrated to synthesize single-atom site catalysts at room temperature. Under regulation of the graphene oxide membrane, a bulk Fe plate was directly converted into Fe single atoms, and the diffusion rate of Fe ions was greatly reduced, resulting in an ultralow concentration of Fe2+ around the working electrode, which successfully prevented the growing of nuclei and aggregating of metal atoms. Monatomic Fe atoms are homogeneously anchored on the as-prepared nitrogen-doped carbon. Owing to the fast photoelectron injection from photosensitizers to atomically dispersed Fe sites through the highly conductive supported N-C, the Fe-SAs/N-C exhibits an outstanding photocatalytic activity toward CO2 aqueous reduction into syngas with a tunable CO/H2 ratio under visible light irradiation. The gas evolution rates for CO and H2 are 4500 and 4950 μmol g–1 h–1, respectively, and the tunable CO/H2 ratio is from 0.3 to 8.8. This article presents an efficient strategy to develop the single-atom site catalysts and bridges the gap between heterogeneous and homogeneous catalysts toward photocatalytic CO2 aqueous reduction into syngas.

Molecular Engineering toward Pyrrolic N‐Rich M‐N4 (M = Cr, Mn, Fe, Co, Cu) Single‐Atom Sites for Enhanced Heterogeneous Fenton‐Like Reaction

“…Till now, there are still many challenges to be addressed, such as the precise regulation of the atomic configurations and scale‐up synthesis of SACs. [ 7 ] Moreover, the mechanisms underlying the SACs‐mediated catalytic processes are not well understood.…”

Single‐Atom Catalysts Derived from Metal–Organic Frameworks for Electrochemical Applications

“…Reproduced with permission. [ 19b ] Copyright 2020, Elsevier Ltd. c) Synthesis of Fe/OES with controlled structures by pyrolysis of core–shelled Fe/ZIF‐8@SiO x composites. Reproduced with permission.…”

“…Owing to their tunable electronic structure and low‐coordinated configuration, SACs have displayed attractive applications in electrochemical energy conversion and storage, such as oxygen reduction reaction (ORR), [ 16 ] oxygen evolution reaction (OER), [ 17 ] hydrogen evolution reaction (HER), [ 18 ] carbon dioxide reduction reaction (CO 2 RR), [ 19 ] and nitrogen reduction reaction (NRR). [ 20 ] Because these SACs are generally single‐metal atoms decorated on metal oxide, [ 21 ] nitride, [ 22 ] or carbon, [ 23 ] the supports are of significant importance for their chemical properties.…”

“…To achieve atomically dispersed separation and isolation of atoms and to prevent the as‐formed single atoms from migration and agglomeration, a variety of synthetic strategies have been reported for the development of SACs, such as pyrolysis, [ 24 ] wet chemistry synthesis, [ 25 ] physical and chemical vapor deposition, [ 26 ] electrochemical deposition, [ 27 ] photoreduction process, [ 21 ] and so on. To date, many noble or non‐noble metal‐based SACs, such as Pt, [ 28 ] Pd, [ 21,28a ] Au, [ 29 ] Ru, [ 30 ] Zn, [ 31 ] Fe, [ 32 ] Co, [ 33 ] Ni, [ 34 ] Mn, [ 16a,35 ] Cu, [ 19c,36 ] etc., have been synthesized through the above mentioned approaches. However, fabricating SACs and maintaining the metal centers as atomically dispersed sites under both synthesis and catalysis conditions are challenging.…”

Which is Better for Nanomedicines: Nanocatalysts or Single‐Atom Catalysts?

“…[101] Wang et al developed a voltage gauged electrofiltration method to synthesize SACs. [102] In detail, by controlling the graphene oxide (GO) film, bulk Fe plate was directly converted into single Fe atoms and the diffusion rate of Fe ions was greatly reduced. The single atom of iron was homogeneously fixed to the nitrogen-doped carbon.…”