Highly active and stable AuNi dendrites as an electrocatalyst for the oxygen reduction reaction in alkaline media

AuNi hierarchical dendrites were fabricated by a facile electrodeposition and dealloying method with exceptional ORR activity and remarkable long-term stability.</p

The complete chloroplast genome of Cratoxylum cochinchinense (Hypericaceae)

Cratoxylum cochinchinense (Lour.) Blume is a tropical Asia specie limited distributed from South China to Borneo. The complete chloroplast genome of the species was found to be 157,103 bp in length, with 129 unique genes, including 37 tRNA, eight rRNA, and 84 protein-coding genes. The GC content of C. cochinchinense is 36.2%. As the first complete chloroplast genome in Hypericaceae, it shows the phylogenetic relationship within Malphigiales

Dilute Au-Containing Ag Nanosponges as a Highly Active and Durable Electrocatalyst for Oxygen Reduction and Alcohol Oxidation Reactions

Zero-dimensional nanoparticles (NPs) have been demonstrated as the promising class of catalysts for various chemical and electrochemical reactions. However, the emerging Au–Ag NP catalysts suffer from single functionality, limited activity enhancement, and unsatisfactory stability problems. Here, we report a facile kinetically controlled solution method to prepare a new class of Au–Ag nanoporous sponges (NSs) composed of three-dimensional networks without using additional stabilizing agents at room temperature. The unexpected shift of the d-band center in our Au–Ag NSs was observed for the first time in Au–Ag bimetallic systems, which effectively activates the Au–Ag NSs for electrochemical reactions. The robust electronic effect coupled with abundant accessible active sites from the hierarchically porous architecture make the bare Au–Ag NSs a superior multifunctional catalyst for oxygen reduction, ethylene glycol (EG) oxidation, and glucose oxidation reactions compared to the commercial Pt/C electrocatalyst in alkaline medium. The optimized AuAg_3.2 NSs deliver a mass activity of 1.26 A mg_Au^–1 toward oxygen reduction reaction, which is ∼8.2 times as high as that of the Pt/C electrocatalyst, simultaneously showing outstanding stability with negligible activity decay after 10 000 cycles. For the anodic reactions, these AuAg_3.2 NSs show extremely high activity and stability toward both EG and glucose catalytic oxidation reactions with a higher mass activity of 7.58 and 1.48 A mg_Au^–1, about 3- and 18.5-fold enhancement than Pt/C, respectively. This work provides important insights into the structural design, performance optimization, and cost reduction to promote the practical applications of liquid fuel cells

A Turbulent Mass Diffusivity Model for Predicting Species Concentration Distribution in the Biodegradation of Phenol Wastewater in an Airlift Reactor

In this study, a three-dimensional CFD transient model is established for predicting species concentration distribution in the biodegradation of phenol in an airlift reactor (ALR). The gas–liquid flow in the ALR is determined by the Euler–Euler method coupled with the standard k-ε model, and the bubble size is predicted by the population balance model (PBM). A turbulent mass diffusivity model is developed to simulate the turbulent mass transfer process and to predict the species concentration distribution. No empirical methods are needed as the turbulent mass diffusivity can be expressed by the concentration variance c2¯ and its dissipation rate εc. A good agreement is found between simulated and experimental results in the literature. It is not reasonable to assume a constant turbulent Schmidt number because the calculated distribution of turbulent mass diffusivity is not identical to that of turbulent viscosity. Finally, the hydrodynamic characteristics and biodegradation performance of the proposed model in a novel ALR are compared with that in the original ALR