•Hollow CuS nano/micro shells were self-assembled by S. oneidensis MR-1.•S. oneidensis MR-1 acted as a biotemplate and a sulfur supplier.•EPS acted as nucleation site for the biofabrication of CuS nanoparticles.•CuS nanorods aggregated to self-assemble a hollow CuS shell extracellularly.•CuS shell enhanced the adsorption ability of S. oneidensis MR-1 to Cr (VI).In the present study, Shewanella oneidensis MR-1 was successfully exploited to produce CuS nanocrystals not only as a biotemplate but also as a supplier of sulfur source. The biogenic H2S produced via the thiosulfate reduction in periplasm grabbed Cu(II) ions bound with extracellular polymeric substance of Shewanella and precipitated as monodisperse CuS nanoparticles extracellularly. These nanoparticles aggregated in the extracellular matrix gradually and then formed CuS nanorods. Ultimately, a complex hollow CuS microshell self-assembled on the cell surface was observed for the first time. The biogenic CuS microshell could significantly enhance the adsorption ability of S. oneidensis MR-1 toward Cr(VI). This work may facilitate a better understanding about the biosynthesis mechanism of nanomaterials and contribute to the application in environmental remediation.Download high-res image (193KB)Download full-size image

The enhanced electricity generation in a biocathode bio-electrochemical system (BES) with Microcystis aeruginosa IPP as the cathodic microorganism under illumination is investigated. The results show that this cyanobacterium is able to act as a potential cathodic microorganism under illumination. In addition, M. aeruginosa IPP is found to produce reactive oxygen species (ROS) in its growth in the BES. ROS, as more competitive electron acceptors than oxygen, are utilized prior to oxygen. The BES current is substantially reduced when the ROS production is inhibited by mannitol, indicating that the ROS secreted by the cyanobacterium play an important role in the electricity generation of such a biocathode BES. This work demonstrates that the ROS released by cyanobacteria benefit for an enhanced electricity generation of BES.Highlights► M. aeruginosa can act as a cathodic microorganism under illumination in a biocathode BES. ► M. aeruginosa IPP is able to produce ROS in its growth in BES. ► ROS released by cyanobacteria benefit for an enhanced electricity generation.

Microbial fuel cells (MFC) provide a new opportunity for simultaneous electricity generation and waste treatment. An improvement in the anode capacity of MFCs is essential for their scale-up and commercialization. In this work we demonstrate, for the first time, that plasma-based ion implantation could be used as an effective approach to modify carbon paper as an anode for MFC to improve its electricity-generating capacity. After the N+ ion implantation, a decreased charge-transfer resistance is achieved, which is attributed to the increased C–N bonds after N+ ion implantation. In addition, the surface roughness and hydrophobicity are also changed, which favor microbial adhesion on the anode surface. The cyclic voltammetry results show that both the electrochemical activity and the electron transfer are enhanced remarkably, leading to better MFC performance compared to the control. Such a plasma surface modification technique provides an effective way to modify the electrode for enhancing MFC performance for power generation.

Microbial fuel cells (MFC) provide a new opportunity for simultaneous electricity generation and waste treatment. An improvement in the anode capacity of MFCs is essential for their scale-up and commercialization. In this work we demonstrate, for the first time, that plasma-based ion implantation could be used as an effective approach to modify carbon paper as an anode for MFC to improve its electricity-generating capacity. After the N+ ion implantation, a decreased charge-transfer resistance is achieved, which is attributed to the increased C–N bonds after N+ ion implantation. In addition, the surface roughness and hydrophobicity are also changed, which favor microbial adhesion on the anode surface. The cyclic voltammetry results show that both the electrochemical activity and the electron transfer are enhanced remarkably, leading to better MFC performance compared to the control. Such a plasma surface modification technique provides an effective way to modify the electrode for enhancing MFC performance for power generation.