PtCo catalyst with modulated surface characteristics for the cathode of direct methanol fuel cells

摘要

A PtCo catalyst with an ordered cubic primitive structure was synthesized and investigated for the application as a cathode in direct methanol fuel cells. The synthesis involved the preparation of an amorphous PtOx/C precursor by the sulfite complex route, an impregnation with Co(NO_3)_2, a high temperature (800℃) carbothermal reduction and, finally, a leaching procedure. This method led to the occurrence of a Pt_3Co/C catalyst with a primitive cubic ordered (L1_2) phase and a mean crystallite size of 3.3 nm, as well as a suitable degree of alloying. This electrocatalyst was investigated for the oxygen reduction reaction in a direct methanol fuel cell (DMFC) operating in the range 30-90℃. At 60℃, under atmospheric pressure, a maximum power density of 40 mW cm~(-2) was obtained with the new PtCo catalyst formulation at low noble metal loading on the electrode (1 mg cm~2). This performance was 2.3 times higher than a benchmark Pt catalyst used for comparison.