Elucidating the electrocatalytic activities of Pr-doped PtTiP nanocomposites for hydrogen evolution and methanol oxidation reactions

Abstract

Developing bifunctional electrocatalysts that combine high catalytic activity with long-term stability remains a major challenge in electrochemical energy conversions. Efficient hydrogen production via water splitting and methanol oxidation in direct methanol fuel cells are pivotal to realizing sustainable energy systems. However, few catalysts exhibit outstanding performance in both reactions. In this regard, we develop a praseodymium-doped platinum-titanium phosphide catalyst on modified nitrogen-doped multiwalled carbon nanotubes (PrPtTiP/N-MWCNT). Under acidic conditions (0.3 m H2SO4), PrPtTiP/N-MWCNT exhibits ultralow overpotentials of 8.2 and 12.2 mV at 10 and 100 mA cm- 2, respectively, which are substantially lower than those of PtP/N-MWCNT and commercial Pt/C. The developed catalyst maintains high activity at elevated current densities of up to 150 mA cm- 2 with minimal performance degradation. For methanol oxidation, PrPtTiP/N-MWCNT delivers a mass activity of 5.83 A mg-1 Pt, i.e., 3.3- and 8.3-fold enhancements over PtP/N-MWCNT and Pt/C, respectively. Comprehensive electrochemical, structural, and computational analyses confirm the excellent durability of the catalyst over 10,000 potential cycles and during prolonged chronoamperometric operation. Collectively, these results position PrPtTiP/N-MWCNT as a robust and highly active bifunctional electrocatalyst for hydrogen evolution and methanol oxidation in acidic environments.