Pulse-opencircuit voltammetry: A novel method characterizes bioanode performance from microbe-electrode interfacial processes.

Bioanode is a key component of bioelectrochemical systems, but the methods characterizing its resistance distribution are lacked. We propose a novel pulse-opencircuit voltammetry (POV) based on the analytical principle clarified from the electron flow pathways of microbe-electrode interfacial processes (MEIPs). A dual-cathode cell is designed to provide an experimental platform for ensuring precise data acquisition of bioanodes. This POV method enables to measure steady state polarization curves and ohmic potential loss curves by integrating potentiostatic discharge and current interruption techniques. They determines reaction resistance (RB,act) and ohmic resistance (RB,ohm) of biofilm with the assistance of impedance spectroscopy measuring material resistance. The results of various bioanodes demonstrate that RB,act is the principal limiting factor and its value relies on catabolism state. Whilst RB,ohm is relevant to extracellular electron transfer behaviors. They are two useful indicators of the dynamic evaluation of biofilm. We anticipate that this method together with the cell platform is accessible to users and has wide applications in bioanode construction and electroactive bacteria investigation.

Efficient photocatalytic debromination of 2,2',4,4'-tetrabromodiphenyl ether by Ag-loaded CdS particles under visible light.

Highly active and visible light-driven Ag-loaded CdS photocatalysts were prepared via a hydrothermal synthesis and photodeposition method. The removal and debromination of 2,2',4,4'-tetrabromodiphenyl ether was achieved efficiently using this Ag-loaded CdS under visible light, with a removal efficiency of 100% and a debromination ratio of 44.3% being achieved within 30 min. Both the reaction solvent and the water content were found to have a strong influence on the removal efficiency and the debromination ratio. In addition, the stepwise debromination preference was ortho ≫ para, thereby indicating that the main debromination pathway was electron reduction. The stability and efficiency of these Ag-loaded CdS photocatalysts for the removal of BDE47 were satisfactory, and so our results confirmed the development of a promising visible light-driven catalyst for the removal of polybrominated diphenyl ethers.

Efficient photocatalytic degradation of tetrabromodiphenyl ethers and simultaneous hydrogen production by TiO2-Cu2O composite films in N2 atmosphere: Influencing factors, kinetics and mechanism.

TiO2-Cu2O photocatalyst composite film with a heterostructure was synthesized on a copper substrate for 2,2',4,4'-tetrabromodiphenyl ether (BDE47) reduction. First, Cu2O film was synthesized by the electrochemical deposition method, and then TiO2 was coated on the surface of the Cu2O film. The morphology, surface chemical composition and optical characteristics of TiO2-Cu2O film were characterized. The degradation efficiency of BDE47 and hydrogen production by TiO2-Cu2O films was higher than those by pure TiO2 or Cu2O films. The highest BDE47 degradation efficiency of 90% and hydrogen production of 12.7mmolLliq-1 after 150min were achieved by 67%TiO2-Cu2O films. The influencing factors were investigated in terms of film component, solvent condition, and initial pH. A kinetics study demonstrated that BDE47 degradation followed a pseudo-first-order model. Photocatalytic apparent reaction rate constant of BDE47 by TiO2-Cu2O films was 0.0070min-1, which was 3.3 times of that by directly photolysis process. During photocatalytic debrmination process, the photogenerated holes were reserved in the valance band of Cu2O to oxidize methanol. Meanwhile, the partial photogenerated electrons transferred to the conduction band of TiO2 and directly eliminated the ortho-Br of BDE47 and yielded BDE28 and BDE15. The other partial photogenerated electrons reduced protons (H+) to form atomic hydrogen (H°), which could substitute the para-Br of BDE47 and generated BDE17 and produce hydrogen.