Monitoring Electron Flow in Nickel Single-Atom Catalysts during Nitrogen Photofixation

Abstract

An efficient catalytic system for nitrogen (N2) photofixation generally consists of light-harvesting units, active sites, and an electron-transfer bridge. In order to track photogenerated electron flow between different functional units, it is highly desired to develop in situ characterization techniques with element-specific capability, surface sensitivity, and detection of unoccupied states. In this work, we developed in situ synchrotron radiation soft X-ray absorption spectroscopy (in situ sXAS) to probe the variation of electronic structure for a reaction system during N2 photoreduction. Nickel single-atom and ceria nanoparticle comodified reduced graphene oxide (CeO2/Ni-G) was designed as a model catalyst. In situ sXAS directly reveals the dynamic interfacial charge transfer of photogenerated electrons under illumination and the consequent charge accumulation at the catalytic active sites for N2 activation. This work provides a powerful tool to monitor the electronic structure evolution of active sites under reaction conditions for photocatalysis and beyond.

Photoinduced Metastable Asymmetric Cu Single Atoms for Photoreduction of CO2 to Ethylene

“…[ 20 ] The enhanced photocurrent responses and the smaller semicircle in the electrochemical impedance spectra (EIS) indicate the inhibited carrier recombination and accelerated carrier‐transfer kinetics in Cu 1 /TiO 2 , respectively (Figure S18, Supporting Information). [ 20,21 ]…”

“…[20] The enhanced photocurrent responses and the smaller semicircle in the electrochemical impedance spectra (EIS) indicate the inhibited carrier recombination and accelerated carriertransfer kinetics in Cu 1 /TiO 2 , respectively (Figure S18, Supporting Information). [20,21] Furthermore, we carried out in situ measurements to monitor the structural conversion in Cu 1 /TiO 2 . In situ XANES spectra at Cu K-edge were recorded under different conditions (Figure S19, Supporting Information).…”

A bioinspired floatable system with a 3D sandwich-type triphase interface for highly efficient nitrogen fixation

“…† Because of the sluggish kinetics in the O 2 evolution process, the yields of O 2 and NH 3 were not in a stoichiometric ratio in a short-time procedure. [72][73][74] As the reaction time is prolonged, the ratio of the generated NH 3 (624.87 mmol g cat −1 h −1 ) and O 2 (456.64 mmol g cat −1 h −1 ) tends to be stoichiometric.…”

Noble‐Metal‐Free Single‐ and Dual‐Atom Catalysts for Artificial Photosynthesis

“…Pan, Zheng, and co‐workers recently anchored isolated Ni atoms on reduced graphene oxide (GO) decorated by ceria (CeO 2 ) NPs (denoted as CeO 2 /Ni‐G). [ 141 ] In detail, a GO aqueous solution containing CeCl 3 ·6H 2 O and NiCl 2 ·6H 2 O was freeze‐dried and calcinated at 300 °C for 1 h, then annealed at 550 °C for 2 h under Ar atmosphere to obtain CeO 2 /Ni‐G composites. The as‐synthesized CeO 2 /Ni‐G composites were examined to photocatalyze N 2 gas with a NH 3 production rate of 428 µmol g −1 h −1 under full‐spectrum Xe lamp irradiation (Figure 10F).…”