Additional file 1: of Cell-bound lipases from Burkholderia sp. ZYB002: gene sequence analysis, expression, enzymatic characterization, and 3D structural model

All PCR conditions and PCR procedures used in this research. (DOC 54 kb

Efficient Oxygen Reduction Electrocatalyst Based on Edge-Nitrogen-Rich Graphene Nanoplatelets: Toward a Large-Scale Synthesis

The large-scale synthesis of nitrogen doped graphene (N-graphene) with high oxygen reduction reaction (ORR) performance has received a lot of attention recently. In this work, we have developed a facile and economical procedure for mass production of edge-nitrogen-rich graphene nanoplatelets (ENR-GNPs) by a combined process of ball milling of graphite powder (GP) in the presence of melamine and subsequent heat treatment. It is found that the ball milling process can not only crack and exfoliate pristine GP into edge-expanded nanoplatelets but also mechanically activate GP to generate appropriate locations for N-doping. Analysis results indicate that the doped N atoms mainly locate on the edge of the graphitic matrix, which contains ca. 3.1 at.% nitrogen content and can be well-dispersed in aqueous to form multilayer nanoplatelets. The as-prepared ENR-GNPs electrocatalyst exhibits highly electrocatalytic activity for ORR due to the synergetic effects of edge-N-doping and nanosized platelets. Besides, the stability and methanol tolerance of ENR-GNPs are superior to that of the commercial Pt/C catalyst, which makes the nanoplatelets a promising candidate for fuel cell cathode catalysts. The present approach opens up the possibility for simple and mass production of N-graphene based electrocatalysts in practice

Identifying the Active Site in Nitrogen-Doped Graphene for the VO²⁺/VO₂⁺ Redox Reaction

Nitrogen-doped graphene sheets (NGS), synthesized by annealing graphite oxide (GO) with urea at 700–1050 °C, were studied as positive electrodes in a vanadium redox flow battery. The NGS, in particular annealed at 900 °C, exhibited excellent catalytic performance in terms of electron transfer (ET) resistance (4.74 ± 0.51 and 7.27 ± 0.42 Ω for the anodic process and cathodic process, respectively) and reversibility (Δ<i><i>E</i></i> = 100 mV, <i>I</i>_pa/<i>I</i>_pc = 1.38 at a scan rate of 50 mV s^–1). Detailed research confirms that not the nitrogen doping level but the nitrogen type in the graphene sheets determines the catalytic activity. Among four types of nitrogen species doped into the graphene lattice including pyridinic-N, pyrrolic-N, quaternary nitrogen, and oxidic-N, quaternary nitrogen is verified as a catalytic active center for the [VO]²⁺/[VO₂]⁺ couple reaction. A mechanism is proposed to explain the electrocatalytic performance of NGS for the [VO]²⁺/[VO₂]⁺ couple reaction. The possible formation of a N–V transitional bonding state, which facilitates the ET between the outer electrode and reactant ions, is a key step for its high catalytic activity

Syntheses, Crystal Structures, and Properties of Four Metal–Organic Complexes Based on 1,4,5,6,7,7-Hexachlorobicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic Acid

Four metal–organic complexes [Ni­(HET)­(phen)­(H₂O)]­·(HET)­·H₂O (<b>1</b>), [Cu­(HET)­(phen)­(H₂O)]­·1.5H₂O (<b>2</b>), [Cu₂(HET)₂­(bipy)_1.5­(H₂O)]­<b>·</b>15DMF<b>·</b>2H₂O (<b>3</b>), and [Cd₂O­(HET)₂­(bipy)­(H₂O)]­<b>·</b>2H₂O<b>­·</b>EtOH (<b>4</b>) (HET = 1,4,5,6,7,7-hexachlorobicyclo[2.2.1]­hept-5-ene-2,3-dicarboxylic acid, phen = 1,10-phenanthroline, bipy = 4,4′-bipyridine) have been synthesized via hydro- or solvothermal reactions. It was found that complexes <b>1</b> and <b>2</b> are two-dimensional (2D) structures built from discrete complexes via the typical intermolecular interactions, and there was a closed loop built from the lattice water and carboxylate groups in <b>1</b> through intramolecular hydrogen bonds. Complex <b>3</b> exhibits three-dimensional (3D) structure with 5-connected <i><b>bnn</b></i> hexagonal BN topology. Complex <b>4</b> features a non-interpenetrating <i><b>sql</b></i> 2D coordination network, which is further linked into a 3D structure by C–H···Cl weak interaction. The properties of magnetism, fluorescence, and electrochemistry have also been investigated in this paper