Co-and N-doped carbon nanotubes with hierarchical pores derived from metal-organic nanotubes for oxygen reduction reaction

Biomolecules with a broad range of structure and heteroatom-containing groups offer a great opportunity for rational design of promising electrocatalysts via versatile chemistry.In this study,uniform folic acid-Co nanotubes(FA-Co NTs) were hydrothermally prepared as sacrificial templates for highly porous Co and N co-doped carbon nanotubes(Co-N/CNTs) with well-controlled size and morphology.The formation mechanism of FA-Co NTs was investigated and FA-Co-hydrazine coordination interaction together with the H-bond interaction between FA molecules was characterized to be the driving force for growth of one-dimensional nanotubes.Such distinct metal-ligand interaction afforded the resultant CNTs rich Co-N_x sites,hierarchically porous structure and Co nanoparticle-embedded conductive network,thus an overall good electrocatalytic activity for oxygen reduction.Electrochemical tests showed that Co-N/CNTs-900 promoted an efficient 4 e ORR process with an onset potential of 0.908 V vs.RHE,a limiting current density of 5.66 mA cm^(-2) at 0.6 V and a H_2 O_2 yield lower than 5%,comparable to that of 20%Pt/C catalyst.Moreover,the catalyst revealed very high stability upon continuous operation and remarkable tolerance to methanol.

Adsorptions of metal adatoms on graphene-like BC3 and their rich electronic properties： A first-principles study

Density functional calculations have been performed to investigate the adsorption of twenty two different kinds of metal adatoms on graphene-like BC3. In contrast to the graphene adsorbed with adatoms, the BC3 with adatoms shows many interesting properties.（1） The interaction between the metal adatoms and the BC3 sheet is remarkably strong. The Li, Na, K, and Ca possess the binding energies larger than the cohesive energies of their corresponding bulk metals.（2）The Li, Na, and K adatoms form approximately ideal ionic bonds with BC3, while the Be, Mg, and Ca adatoms form ionic bonds with BC3 with slight hybridization of covalent bonds. The Al, Ga, In, Sn, and all transition metal adatoms form covalent bonds with BC3.（3） For all the structures studied, there exhibit metal, half-metal, semiconducting, and spin-semiconducting behaviors. Especially, the BC3 with Co adatom shows a quantum anomalous Hall（QAH） phase with a Chern number of -1 based on local density approximation calculations.（4） For Li, Na, K, Ca, Ga, In, Sn, Ti, V, Cr,Ni, Pd, and Pt, there exists a trend that the adatom species with lower ionization potential have lower work function. Our results indicate the potential applications of functionalization of BC3 with metal adatoms.

H3K36 Methylation Is Involved in Promoting Rice Flowering

Dear Editor, Histone H3 lysine 36 （H3K36） methylation is a conserved epigenetic mark in all eukaryotes （Berr et al., 2011; Wagner and Carpenter, 2012）. Reverse genetic analysis in Arabidopsis had uncovered a crucial role of H3K36 di- and tri-methylation （H3K36me2 and H3K36me3） in flowering-time regulation （reviewed in Berr et al., 2011）.