SizeDependent Activity of Co3O4 Nanoparticle （SizeDependent Co3O4纳米粒子的活性）.pdfVIP

15068 J. Phys. Chem. C 2009, 113, 15068–15072 Size-Dependent Activity of Co O Nanoparticle Anodes for Alkaline Water Electrolysis 3 4 Arthur J. Esswein, Meredith J. McMurdo, Phillip N. Ross, Alexis T. Bell,* and T. Don Tilley* Departments of Chemistry and Chemical Engineering, Uni Versity of California, Berkeley, Berkeley, California 94720, and the Chemical Sciences Di Vision, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 Recei Ved: April 30, 2009; ReVised Manuscript ReceiVed: July 10, 2009 Cubic Co O nanoparticles with average diameters of 5.9, 21.1, and 46.9 nm (hereafter small, medium, and 3 4 large) have been synthesized and characterized by pXRD, TEM, and BET. The nanoparticles were loaded onto Ni foam supports for evaluation as anodes for water electrolysis in 1.0 M KOH. Current densities of 10 mA/cm2 were achieved at overpotentials of 328, 363, and 382 mV for anodes loaded with 1 mg/cm2 of small, medium, and large sized Co O nanoparticles, respectively. The activity correlates with the BET surface area 3 4 of the isolated particles. A plot of the electrochemical overpotential at 10 mA/cm2 against the log of the BET g r surface area gives a linear relation with a slope of -47 ( 7 mV/dec, showing unequivocally that the activ