Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are two major processes in renewable energy technologies. However, discovering high performance bifunctional electrocatalyst for OER and ORR still remains a tremendous challenge. Herein, we present effective bifunctional electrocatalysts Co/Co 3 O 4 /Co(OH) 2 /N-doped mesoporous carbon (Co-NC) via one-pot synthesis. As resulted, the bestperforming Co-NC 750 consists of the highest amounts of pyridinic nitrogen and optimized ratio of three cobalt species. The strong confinement effect between Co/Co 3 O 4 /Co(OH) 2 core and N-graphitic shell of Co-NC 750 leads to excellent ORR activity and superior OER performance, along with a low reversible overvoltage of 1.02 V between ORR and OER under alkaline environment, endowing it economical and efficient for reversible oxygen electrode reactions. In addition, we discovered a potential research direction of advancing bifunctional catalysts with synergy effect by optimizing metal crystal structures and doping nitrogen to accelerate oxygen electrode reactions merely by altering its pyrolyzation temperatures.[a] Dr.
Graft copolymerization of diethylenetriamine onto bagasse celluloses was investigated with ammonium ceric nitrate as initiator in an aqueous medium. The condition of the graft copolymerization initiator concentration, the mass ratio of monomer/cellulose, reaction temperature, reaction time based on the experiment is optimized according to the zeta potential. The results showed the relative optimum process conditions were: the concentration of initiator at 36.98mmol/L, the mass ratio of the monomer and cellulose at 1:1, the reaction temperature at 70°C, and the reaction time by 3h. In addition, the graft copolymers were characterized by Fourier transform infrared spectra (FT-IR), X-ray diffraction analysis (XRD). The results showed that bagasse celluloses could be grafted with diethylenetriamine in aqueous medium.
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