Residual Porosity of 3D-LAM-Printed Stainless-Steel Electrodes Allows Galvanic Exchange Platinisation

Stainless-steel rods were manufactured by laser additive manufacturing (LAM or "3D-printing") from a stainless-steel (316 L) powder precursor, and then investigated and compared to conventional stainless steel in electrochemical experiments. The LAM method used in this study was based on "powder bed fusion", in which particles with an average diameter of 20-40 mm are fused to give stainless-steel rods of 3 mm diameter. In contrast to conventional bulk stainless-steel (316 L) electrodes, for 3D-printed electrodes, small crevices in the surface provide residual porosity. Voltammetric features observed for the 3D-printed electrodes immersed in aqueous phosphate buffer are consistent with those for conventional bulk stainless steel (316 L). Two chemically reversible surface processes were observed and tentatively attributed to Fe(II/III) phosphate and Cr(II/III) phosphate. Galvanic exchange is shown to allow improved platinum growth/adhesion onto the slightly porous 3D-printed stainless-steel surface, resulting in a mechanically robust and highly active porous platinum deposit with good catalytic activity toward methanol oxidation.