Enhanced bioelectrochemical performance of microbial fuel cell with titanium dioxide-attached dual metal organic frameworks grown on zinc aluminum - layered double hydroxide as cathode catalyst.

In this study, a three-step distributed feeding method was used to prepare TiO2-attached dual CoZn-metal organic frameworks growing on ZnAl-layered double hydroxide (TiO2@ZIF-67/ZIF-8@ZnAl-LDH) as cathode catalyst of microbial fuel cell (MFC). The composite material was a composite core-shell structure constructed by multi-layer coating with sheet-like ZnAl-LDH as the base, dual MOFs as the magnetic core and TiO2 as the rough surface. The composite material had crystal planes (009), (110), (101) interface. The rough surface, core-shell core and polyhedral structure of TiO2@ZIF-67/ZIF-8@ZnAl-LDH were observed. The complete distribution of Ti, Zn, Al, and Co in the material was observed and offered active sites. The contents of Ti (15.97 %), Al (5.53 %), Na (5.04 %), N (3.52%), Zn (1.47 %) were found out. TiO2@ZIF-67/ZIF-8@ZnAl-LDH was excellent in electrochemical activity and the maximum power density was 409.6 mW/m2, the stable continuous output voltage was 538.4 mV for 8 d.

Improving oxygen reduction reaction of microbial fuel cell by titanium dioxide attaching to dual metal organic frameworks as cathode.

In this study, a two-step simple distributed feeding method was used to prepare the core-shell nanocomposite dual metal organic frameworks (D-MOFs, TiO2@ZIF-67/ZIF-8). There were three obvious peaks (011), (112), (222) interface in D-MOFs core, which fully showed that ZIF-67/ZIF-8 crystal core was successfully synthesized. The morphology of composite material was core-shell structure with a rough surface, and Ti, Co, Zn, Al were uniformly distributed on the surface. TiO2@ZIF-67/ZIF-8 also had excellent electrochemical activity and the maximum power density of TiO2@ZIF-67/ZIF-8 microbial fuel cell (MFC) was 341.506 mW/m2, which was 1.30 times of ZIF-67/ZIF-8-MFC (262.144 mW/m2) and 2.07 times of ZIF-67-MFC (164.836 mW/m2). And the continuous output voltage of TiO2@ZIF-67/ZIF-8-MFC was 413.43 mV, which could maintain stable voltage output for 8.3 days. D-MOFs as the core of composites ensured the integrity, stability and high activity of materials; Rough TiO2 as the surface of the material provided surface area and reaction center.

Improved electrochemical performances by Ni-catecholate-based metal organic framework grown on NiCoAl-layered double hydroxide/multi-wall carbon nanotubes as cathode catalyst in microbial fuel cells.

In this study, a simple two-step hydrothermal method was used to prepare the cathode catalyst of the microbial fuel cell (MFC). NiCoAl- layered double hydroxide (LDH) nanosheets were grown vertically on multi-wall carbon nanotubes (MWCNTs) in situ; Ni-catecholate-based metal organic framework (Ni-CAT MOF) were modified on the surface of the nanosheets. The maximum output voltage of Ni-CAT/NiCoAl-LDH/MWCNTs was 475 mV, the maximum stabilization time was 8 d, the maximum output power was 448.5 ± 12.0 mW/m2, which was 1.03 times that of NiCoAl-LDH/MWCNT-MFC (433.5 ± 14.8 mW/m2) and 1.35 times of NiCoAl-LDH- MFC (329.9 ± 2.9 mW/m2). The layer structure of LDH, conductivity of Ni-CAT and MWCNT improved the flow efficiency of ions between layers and effectively reduced transmission resistance, and these have effectively enhanced the cycle stability and power generation efficiency of the electrode.