Electrochemical synthesis of hierarchical carbon fiber@PPy@PtNi composite for the high-efficient oxygen reduction in seawater medium
摘要
Seawater-dissolved oxygen batteries supplied the electrical power by consuming the seawater-dissolved oxygen for the marine equipment, and have been becoming promising candidates. However, the ultralow oxygen concentration and the strong poisoning effect of Cl− in seawater limited the reaction kinetics. The hierarchical encapsulation composite structure of carbon cloth@polypyrrole@PtNi was fabricated through the electrochemical co-deposition combined with electrochemical polymerization. The characterization results demonstrated that the catalytic layer of PtNi displays a mixing structure of monometallic nanoparticles and alloy nanoparticles with the approximate PtNi atom ratio of 2.5. And the Pt of PtNi composite catalyst displays a preferential growth along the crystal faces of (111) and (200). In natural seawater medium, the carbon cloth@polypyrrole@PtNi-Mg exhibited efficient oxygen reduction catalytic performance. CV test results indicated that the oxygen reduction potential of the cathode composite material was 0.42 V (vs. RHE), with an oxygen reduction peak current density of 4.37 mA cm−2. The battery of carbon cloth@polypyrrole@PtNi-Mg displayed a high stable discharge voltage of 1.15 V at the constant-current density of 1 mA cm−2 in natural seawater without O2 bubbling, which indicated the promising application of carbon cloth@polypyrrole@PtNi as a practical oxygen reduction electrode material in natural seawater.
Graphical abstract