Amorphizing of Au Nanoparticles by CeO_x–RGO Hybrid Support towards Highly Efficient Electrocatalyst for N₂ Reduction under Ambient Conditions

Abstract

Ammonia synthesis is one of the most kinetically complex and energetically challenging chemical processes in industry and has used the Harber-Bosch catalyst for over a century, which is processed under both harsh pressure (150-350 atm) and hightemperature (623-823 K), wherein the energy and capital intensive Harber-Bosch process has a huge energy cost accounting for about 1%-3% of human's energy consumption. Therefore, there has been a rough and vigorous exploration to find an environmentally benign alternative process. As the amorphous material is in a metastable state and has many "dangling bonds", it is more active than the crystallized one. In this paper, CeO -induced amorphization of Au nanoparticles anchored on reduced graphite oxide (a-Au/CeO -RGO) has been achieved by a facile coreduction method under ambient atmosphere. As a proof-of-concept experiment, a-Au/CeO -RGO hybrid catalyst containing the low noble metal (Au loading is 1.31 wt%) achieves a high Faradaic efficiency (10.10%) and ammonia yield (8.3 μg h mg ) at -0.2 V versus RHE, which is significantly higher than that of the crystalline counterpart (c-Au/RGO), and even comparable to the yields and efficiencies under harsh temperatures and/or pressures.

An Amorphous Noble‐Metal‐Free Electrocatalyst that Enables Nitrogen Fixation under Ambient Conditions

“…This outstanding performance in as-obtained noblemetal-free catalyst is even comparable with the yield of N 2 fixation under harsh temperatures and/or pressures (Supporting Information, Table S1). [30,47] As exhibited in Figure 3b and the Supporting Information, Figure S20, no obvious fluctuation arises in the average yields and the current intensities,i mplying asobtained nanostructured BVC-A can guarantee the stability during the catalytic process. The corresponding detection calibration curves are shown in the Supporting Information, Figure S16, S17.…”

“…Asomewhat broader and weaker Raman-active mode accompanied with obvious Raman-band shifts elucidate that the local lattice imperfections,t he maintenance of short-range order,a sw ell as distorted lattices with variations in bonding length and angle arise together in amorphous Bi 4 V 2 O 11 (Figure 2d; Supporting Information, Figure S5). [30] Along with the benefits of amorphization, introducing CeO 2 will establish band alignment with amorphous Bi 4 V 2 O 11 , which might also be conductive to electrocatalytic NRR. [30] Along with the benefits of amorphization, introducing CeO 2 will establish band alignment with amorphous Bi 4 V 2 O 11 , which might also be conductive to electrocatalytic NRR.…”

“…Structural optimization via the amorphization strategy can induce new defective sites to promote catalytic activity. [30] These achievements provide an intriguing picture for constructing an amorphous Bi 4 V 2 O 11 catalyst, which might enable new opportunities to the electrocatalytic NRR. [28,29] For example,i th as been shown that noble-metal Au undergoes progressive amorphization, which contributes to higher activity with respect to the crystalline counterpart for electrocatalytic NRR.…”

Electrocatalytic Hydrogenation of N2to NH3by MnO: Experimental and Theoretical Investigations

“…In N 2 -fixing bacteria, nitrogenases biologically can catalyze the reduction of N 2 to NH 3 at ambient conditions. [6,[9][10][11] This traditional process is not only energy-intensive, but the H 2 used as the feeding gas often comes from fossil fuels leading to serious greenhouse gas emission. [6,[9][10][11] This traditional process is not only energy-intensive, but the H 2 used as the feeding gas often comes from fossil fuels leading to serious greenhouse gas emission.…”

Oxygen Vacancy–Enhanced Electrocatalytic Performances of TiO2 Nanosheets toward N2 Reduction Reaction

“…Alternatively, multiple encouraging strategies, including photocatalysis, mimicking biological nitrogen, and electrocatalysis were gradually developed to realize artificial N 2 fixation at mild conditions. Up to now, although a number of electrocatalysts were investigated, including the metals, [8][9][10][11] the metal oxide or sulfide, [12][13][14] and metal-free compounds, [15][16][17] there are still many shortcomings. [6] It has been extensively reported that heterogenous catalysts play vital roles in breaking or lowing the energy barrier required in the rate-determining step in electroreduction from N 2 to NH 3 , [7] which is the key in further improving N 2 reduction reaction (NRR) performances.…”