期刊
NANO RESEARCH
卷 14, 期 11, 页码 4211-4219出版社
TSINGHUA UNIV PRESS
DOI: 10.1007/s12274-021-3373-4
关键词
electrocatalysis; N-2 reduction; BN nanosheet; spin state; single-atom catalyst; jdensity functional theory (DFT)
类别
资金
- National Natural Science Foundation of China [21673137]
- Science and Technology Commission of Shanghai Municipality [16ZR1413900]
- Program for Top Talents in Songjiang District of Shanghai
- Scientific Data and Computing Center, a component of the Computational Science Initiative, at Brookhaven National Laboratory [DE-SC0012704]
This study theoretically investigates the electrocatalytic N-2 reduction performance of nine prototypical single-metal-atom active sites (SMASs) embedded in defective BN nanosheets. The results reveal the significant influence of the spin state of SMAS on tuning the potential-determining steps of electrocatalytic N-2 reduction reaction (eNRR), with higher spin states being beneficial for reducing limiting potentials of eNRR. The study provides guidance for catalyst design to enhance eNRR performance by tuning the spin state of the active site, breaking the scaling relations between key N-containing intermediates.
Single-atom catalysts (SACs) especially supported on two-dimensional nitrogen-doped carbon substrate have been widely reported to be able to effectively promote electrocatalytic N-2 reduction reaction (eNRR). The precise design of single-metal-atom active site (SMAS) calls for fundamental understanding of its working mechanism for enhanced eNRR performance. Herein, by means of density functional theory calculations, we theoretically investigate the eNRR performance of nine prototypical SMAS, namely, MN2B2 (M: transition metals of IIIB, IVB and VB groups) which comprises of asymmetric ligands of N2B2 embedded in defective BN nanosheet. Our results reveal the significant role of spin state of SMAS in tuning the potential-determining steps of eNRR, in which MN2B2 site with higher spin magnetic moment (mu) is beneficial to reducing limiting potentials (U-L) of eNRR. Specially, CrN2B2 (mu = 4 mu(B)), VN2B2 (mu = 3 mu(B)) and MoN2B2 (mu = 2 mu(B)) demonstrate high activity and selectivity to eNRR. The asymmetric ligands of N2B2 are deemed to be superior over mono-symmetric ligands. More importantly, our results demonstrate that breaking (or deviating) of the scaling relations between key N-containing intermediates (*N2H/*N-2 and *NH2/*N-2) on MN2B2 can be realized by enhancing spin state of SMAS which renders the active site a balanced N-affinity critical for efficient eNRR. This observation is validated by the calculated Sabatier volcano-shape relation between eNRR limiting potentials and N-2 adsorption energy. Our study develops the guidance for catalyst design to boost eNRR performance by tuning the spin state of an active site.
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