Three-dimensional self-supporting superstructured double-sided nanoneedles arrays of iron carbide nanoclusters embedded in manganese, nitrogen co-doped carbon for highly efficient oxygen reduction reaction.

Nitrogen- and transition metal-dual doped carbon materials with low cost and high catalytic performances are considered as one of promising alternatives for noble metal catalysts in acceleration of oxygen reduction reaction (ORR). In this work, three-dimensional (3D) self-supporting superstructures of iron carbide (Fe3C) nanoclusters entrapped in manganese (Mn)- and nitrogen (N)-dual doped carbon nanosheets covered with double-sided nanoneedles carbon arrays (Fe3C/Mn,N-NCAs) are simply synthesized by a coordination pyrolysis method, in which dicyandiamide mainly behaves as nitrogen source and 1-(2-pyridylazo)-2-naphthol (PAN) as carbon source. Integration of the unique 3D self-supporting superstructures and synergistic effects of the multi-compositions, the as-obtained catalyst displays appealing ORR performance such as the much positive onset potential (Eonset = 0.98 V vs. RHE) and half-wave potential (E1/2 = 0.88 V vs. RHE), as well as a just 10 mV negative shift in E1/2 after 2000 cycles, surpassing commercial Pt/C. This work provides some valuable perspectives for preparation of high-efficiency and low-cost non-noble metal ORR electrocatalysts in energy transformation and storage correlated systems.

Potential of cadmium resistant Burkholderia contaminans strain ZCC in promoting growth of soy beans in the presence of cadmium.

Bioremediation of Cd contaminated environments can be assisted by plant-growth-promoting bacteria (PGPB) enabling plant growth in these sites. Here a gram-negative Burkholderia contaminans ZCC was isolated from mining soil at a copper-gold mine. When exposed to Cd(II), ZCC displayed high Cd resistance and the minimal inhibitory concentration was 7 mM in LB medium. Complete genome analysis uncovered B. contaminans ZCC contained 3 chromosomes and 2 plasmids. One of these plasmids was shown to contain a multitude of heavy metal resistance determinants including genes encoding a putative Cd-translocating PIB-type ATPase and an RND-type related to the Czc-system. These additional heavy metal resistance determinants are likely responsible for the increased resistance to Cd(II) and other heavy metals in comparison to other strains of B. contaminans. B. contaminans ZCC also displayed PGPB traits such as 1-aminocyclopropane-1-carboxylate deaminase activity, siderophore production, organic and inorganic phosphate solubilization and indole acetic acid production. Moreover, the properties and Cd(II) binding characteristics of extracellular polymeric substances was investigated. ZCC was able to induce extracellular polymeric substances production in response to Cd and was shown to be chemically coordinated to Cd(II). It could promote the growth of soybean in the presence of elevated concentrations of Cd(II). This work will help to better understand processes important in bioremediation of Cd-contaminated environment.