The use of galvanic displacement in synthesizing Pt0(Bi)/CNW catalysts highly active in electrooxidation of formic acid

• The galvanic displacement of Bi layers on carbon nanowalls (CNW) by platinum is accomplished.
• The Pt0(Bi)/CNW catalysts are characterized by various methods.
• No dense Pt shells are observed to form.
• The activity of Bi-modified Pt in FAOR is much higher that of Pt/CNW.
• The explanation is given to the observed catalytic effect.

A Pt0(Bi)/CNW catalyst is synthesized by the galvanic displacement of Bi layers sputtered on carbon nanowalls in a PtCl42- solution (with 0.5 M H2SO4 as the supporting electrolyte). The Pt0(Bi)/CNW catalysts are characterized by various methods (SEM, XPS, ICP-AES, OCPT, and CVA). It is shown that nearly 90 at.% Bi is displaced. However, no core–shell structure with a sufficiently dense Pt shell is formed. This is explained by the great difference in the type and parameters of Pt and Bi lattices. The Pt0(Bi)/CNW catalyst exhibits the high stationary specific activity in the formic acid oxidation reaction (FAOR), ∼30 times exceeding (at 200 mV vs. RHE) the activity of Pt electrodeposits on CNW. The catalytic effect is explained by the inhibition of accumulation of strongly chemisorbed species on the bismuth-modified Pt surface and the formation of new active sites for the one-site adsorption of weakly-bound species through which the direct path of the FAOR passes. Thus, the prospects of the practical application of Pt–Bi catalysts highly active in FAOR are demonstrated.