Although single-atomically dispersed metal-Nx on carbon support (M-NC) has great potential in heterogeneous catalysis, the scalable synthesis of such single-atom catalysts (SACs) with high-loading metal-Nx is greatly challenging since the loading and single-atomic dispersion have to be balanced at high temperature for forming metal-Nx. Herein, we develop a general cascade anchoring strategy for the mass production of a series of M-NC SACs with a metal loading up to 12.1 wt%. Systematic investigation reveals that the chelation of metal ions, physical isolation of chelate complex upon high loading, and the binding with N-species at elevated temperature are essential to achieving high-loading M-NC SACs. As a demonstration, high-loading Fe-NC SAC shows superior electrocatalytic performance for O2 reduction and Ni-NC SAC exhibits high electrocatalytic activity for CO2 reduction. The strategy paves a universal way to produce stable M-NC SAC with high-density metal-Nx sites for diverse high-performance applications.

Electrocatalytic N 2 reduction to NH 3 is an attractive method for artificial N 2 fixation at ambient conditions. Herein, we demonstrate that Fe-NC materials could be efficient for electrochemical N 2 reduction reaction (NRR) using iron phthalocyanine (FePc) with a well-defined FeN 4 configuration as a model catalyst. By uniformly loading FePc molecules on porous carbon, it exhibits a high electrocatalytic activity for NRR with a NH 3 yield rate of 137.95 μg h −1 mg −1 FePc at a low potential of −0.3 V (vs RHE). Importantly, by making comparisons with phthalocyanine without the Fe center and performing control and poisoning experiments together with theoretical calculations, we identify the Fe center in FeN 4 as the most active site for NRR among five possible sites in FePc and discover that the preferred route is the alternating pathway of N 2 on Fe. These results open up opportunities for further exploring metal-nitrogen-carbon materials for highly efficient electrochemical N 2 fixation and NH 3 production.

No abstract

Fe/P dual doping synergistically improves the activity and durability of CoS2 polycrystalline nanowire arrays towards efficient hydrogen production.

In a widely used F(2) reciprocal mating population for mapping imprinting genes, we herein propose a genomic imprinting model which describes additive, dominance and imprinting effects of multiple imprinted quantitative trait loci (iQTL) for traits of interest. Depending upon the estimates of the above genetic effects, we categorized imprinting patterns into seven types, which provides a complete classification scheme for describing imprinting patterns. Bayesian model selection was employed to identify iQTL along with many genetic parameters in a computationally efficient manner. To make statistical inference on the imprinting types of iQTL detected, a set of Bayes factors were formulated using the posterior probabilities for the genetic effects being compared. We demonstrated the performance of the proposed method by computer simulation experiments and then applied this method to two real datasets. Our approach can be generally used to identify inheritance modes and determine the contribution of major genes for quantitative variations.

Organic molecules are potential candidates for electrode materials of rechargeable lithium batteries because of their beneficial properties such as cost-effective, environmentally friendly, and sustainable. Until now, the efficient theoretical method to study the organic electrode materials remains elusive. In this paper, an organic electrode material of a lithium battery, Li2C18O8H12·​4H2O, is investigated by the dispersion-corrected density functional theory method. Two outlined points are presented: (1) the method is a powerful tool to predict the geometry structure and the discharge potential of the organic electrode material; and (2) the periodic crystal structure does more to determine the property of the organic electrode material than the single molecular structure. The intermediate structure corresponding to the first discharge plateau is explored, in which the reversible inserted Li ion occupying layers and the unoccupying layers are arranged alternatively. The special structure makes the intermediate state have a closed-shell electron configuration and lowers the electron kinetic energy on the Fermi level of the system. The band gap is about 1.0 eV, which means that the organic electrode material has a good electron conductivity.

No abstract

No abstract