Scalable Synthesis of Low-Pt PtCu₃ Intermetallic Oxygen Reduction Electrocatalysts via Sulfur-Containing Inorganic Salt-Assisted Strategy

Abstract

Proton exchange membrane fuel cells (PEMFCs) as electrochemical-generating devices with zero contaminants can promise a carbon-neutral future, but the usage of the costly platinum group metal catalysts hindered the widespread adoption of PEMFCs. Here, we present the synthesis of a highly active low-Pt PtCu3 intermetallic oxygen reduction catalyst via a sulfur-containing inorganic salt-assisted strategy. We identify that the success of the catalyst synthesis lies in the use of inorganic negative bivalent sulfur salts that leads to the formation of the CuS2 intermediate at low temperatures. The CuS2 intermediate serves as a passivator and releases Cu source at high temperatures to facilitate the formation of the PtCu3 intermetallic catalyst. The prepared small-sized PtCu3 intermetallic catalyst exhibits a high mass-based activity of 3.0 A mgPt–1 and a large electrochemically active surface area of 74 m2 gPt–1 for oxygen reduction, along with an outstanding durability (18% mass activity loss after 30,000 cycles).