A highly biocompatible, hierarchically porous structure comprising macro‐, meso‐ or micropores from cost‐effective bacterial cellulose through a facile carbonization approach, is tailored for its nanopore structure to disclose the mechanism in a porous electrode to enhance direct electrochemistry through endogenous mediator‐based electron transfer between microbes and electrode. The unique mediator‐accessible mesopore structure is necessary to greatly boost anode bioelectrocatalysis.

Surface plasmon resonance imaging (SPRi) is one of the powerful tools for immunoassays with advantages of label-free, real-time, and high-throughput; however, it often suffers from limited sensitivity. Herein we report a dual signal amplification strategy utilizing polydopamine (PDA) functionalization of reduced graphene oxide (PDA-rGO) nanosheets for sensitive SPRi immunoassay in serum. The PDA-rGO nanosheet is synthesized by oxidative polymerization of dopamine in a gentle alkaline solution in the presence of graphene oxide (GO) sheets and then is antibody-conjugated via a spontaneous reaction between the protein and the PDA component. In the dual amplification mode, the first signal comes from capture of the antibody-conjugated PDA-rGO to form sandwiched immunocomplexes on the SPRi chip, followed by a PDA-induced spontaneous gold reductive deposition on PDA-rGO to further enhance the SPRi signal. The detection limit as low as 500 pg mL(-1) is achieved on a nonfouling SPRi chip with high specificity and a wide dynamic range for a model biomarker, carcinoembryonic antigen (CEA) in 10% human serum.

Exploration of sustainable electrocatalysts toward oxygen reduction reaction (ORR) with high catalytic activity remains a key challenge in the development of metal-air batteries and fuel cells. In this work, a hybrid electrocatalyst composed of cobalt (Co/CoO) nanoparticles encapsulated in Co/N-doped mesoporous graphene (Co/CoO@Co/N-graphene) is reported for efficient ORR catalysis. The catalyst is rationally designed and synthesized via a facile combination of spontaneous one-pot polymerization of dopamine in the presence of graphene oxide (GO) and Co ions and the subsequent carbonization process. The morphology, doping nature and ORR activity of the as-prepared catalyst are systematically investigated. It is found that there are abundant Co/N active sites and Co/CoO nanoparticles in this hybrid catalyst, leading to a synergistic enhancement effect for improved ORR activity. In an alkaline environment, this Co/CoO@Co/N-graphene catalyst displays Pt/C-comparable ORR activity in terms of half-wave potential and four-electron reduction selectivity, and higher limiting current density, better methanol tolerant ability and long-term durability. When being evaluated in a Zn-air battery, it demonstrates superior performance to the commercial Pt/C catalyst.

A three-dimensional graphene/nickel composite electrode with a hierarchical porous structure is developed to simultaneously boost the bio- and electro-catalysis for high-performance microbial fuel cells.