Paper based hydrazine monohydrate fuel cells with Cu and C composite catalysts

Self-pumping fuel cells supported on filter papers are constructed by using hydrazine monohydrate as a fuel and potassium permanganate as the oxidant. Cost effective catalysts, namely, Cu nanoparticles (NPs), functionalized multiwalled carbon nanotubes (f-MWCNTs) and Cu-NPs@f-MWCNTs composite are synthesized and loaded onto carbon cloths, which are employed as the electrodes. The cells are operated at room temperature. The Cu-NPs@f-MWCNTs composite contained 75% and 25% of Cu-NPs and fMWCNTs, respectively. The morphology of the composite comprises of Cu-NPs flanked to the tubular structures of f-MWCNTs, which resulted in improved electrocatalytic activity, compared to pristine Cu NPs (which tend to aggregate severely) and pristine f-MWCNTs. The electrocatalytic activities of CuNPs@f-MWCNTs and Cu-NPs are comparable and superior to f-MWCNTs for hydrazine oxidation. Multiple cells with different catalyst combinations at the anode and cathode are electrochemically characterized. The cell with Cu-NPs@f-MWCNTs composite at the anode and with f-MWCNTs at the cathode produced the highest power density of 3.57 mW/cm(2) at 0.89 V. For this catalyst combination, the cell retained an open circuit voltage between 1.85 V - 1.74 V for more than ten minutes of operation. Although the cell current density declined over time, it could be recovered to its original value by replenishing the cell with fresh anolyte and catholyte streams. (C) 2017 Elsevier Ltd. All rights reserved.