Two-Dimensional Mosaic Bismuth Nanosheets for Highly Selective Ambient Electrocatalytic Nitrogen Reduction

Abstract

Electrochemical fixation of N2 to ammonia is a promising strategy to store renewable energy and mitigate greenhouse gas emissions. However, it usually suffers from extremely low ammonia yield and Faradaic efficiency because of the lack of efficient electrocatalysts and the competing hydrogen evolution reaction. Herein, we report that the semiconducting bismuth can be a promising catalyst for ambient electrocatalytic N2 reduction reaction (NRR). A two-dimensional mosaic bismuth nanosheet (Bi NS) was fabricated via an in situ electrochemical reduction process and exhibited favorable average ammonia yield and Faradaic efficiency as high as 2.54 ± 0.16 μgNH3 cm–2 h–1 (∼13.23 μg mgcat. –1 h–1) and 10.46 ± 1.45% at −0.8 V versus reversible hydrogen electrode in 0.1 M Na2SO4. The high NRR electrocatalytic activity of the Bi NS could be attributed to the sufficient exposure of edge sites coupled with effective p-orbital electron delocalization in the mosaic bismuth nanosheets. In addition, the semiconducting feature, which limits surface electron accessibility, could effectively enhance the Faradaic efficiency. This work highlights the potential importance of less reactive main group elements with tunable p-electron density, semiconducting property, and ingenious nanostructure for further exploration of N2 reduction reaction electrocatalysts.

Recent Advanced Materials for Electrochemical and Photoelectrochemical Synthesis of Ammonia from Dinitrogen: One Step Closer to a Sustainable Energy Future

“…In addition to TMs, main group metals, such as Bi, have also drawn attention as 2D NRR electrocatalysts. In 2019, Li et al reported that 2D mosaic Bi nanosheets ( Figure 8 a) exhibited an NH 3 yield of 2.54 ± 0.16 µg cm −2 h −1 and an FE of 10.46 ± 1.45% at −0.8 V versus RHE . This performance was almost tenfold of the 80 nm Bi NPs in the comparison experiment (Figure b).…”

“…b) Comparison of NH 3 yield and Faradaic efficiency of Bi NS and Bi NP. Reproduced with permission . Copyright 2019, American Chemical Society.…”

Greatly Improving Electrochemical N2 Reduction over TiO2 Nanoparticles by Iron Doping

“…[5][6][7][8] Noble metals perform the NRR efficiently;however, their scarcity and high cost limits their application in large-scale N 2 reduction. [12][13][14][15][16][17][18][19][20][21][22][23][24] TiO 2 is highly adaptable as asemiconductor catalyst because of its long-term thermodynamic stability,n atural abundance,a nd nontoxicity. [12][13][14][15][16][17][18][19][20][21][22][23][24] TiO 2 is highly adaptable as asemiconductor catalyst because of its long-term thermodynamic stability,n atural abundance,a nd nontoxicity.…”

Atomic Modulation, Structural Design, and Systematic Optimization for Efficient Electrochemical Nitrogen Reduction

“…It was found that the basal planes of MXene with terminal oxygen required a high energy barrier to perform NRR, while the edge planes with highly exposed Ti sites were advantageous for NRR at a low energy barrier. Very recently, Bi nanosheets with highly exposed edges were fabricated by Li et al The p‐electrons in the Bi atoms at the edges were shown to be delocalized, and positioned favorably for end‐on adsorption and activation of dinitrogen. It was also suggested that a larger charge transfer resistance could assist NRR over HER.…”