Deeply charge-deficient single-atom Pt on highly polar NiInOx for an efficient methanol oxidation reaction

Abstract

The methanol oxidation reaction (MOR) plays a key role in direct methanol fuel cells (DMFCs). Current Pt-based MOR catalysts still face challenges of low Pt atom utilization and weak CO poisoning resistance. Herein, we report a deeply charge-deficient strategy to obtain high-performance single-atom catalysts for the MOR. We synthesized single-atom Pt anchored on hybrid NiInO_x oxides (Pt₁–NiInO_x/CNTs) with Pt–O–Ni/In sites. The highly polar O in Pt–O–Ni/In induces a substantial charge transfer from Pt to NiInO_x, leading to deep charge deficiency. The charge deficiency of single-atom Pt induces strong adsorption of *OH species on NiInO_x and weak adsorption of *CO intermediate on Pt, resulting in high activity and excellent CO poisoning resistance. Pt₁–NiInO_x/CNTs achieves a high mass activity of 18.76 A mg_Pt⁻¹ and retains 92% current density after 5000 cyclic voltammetry cycles. Our work further demonstrates that single-atom Pt anchored on Ni₁₃In₉ alloys (Pt₁–Ni₁₃In₉/CNTs) via metallic Pt–Ni/In bonds shows significantly lower MOR performance. Without the highly polar coordinating O, the charge is transferred from Ni/In to Pt, which enriches the charge density of Pt and results in inferior CO poisoning resistance and poor MOR performance of Pt₁–Ni₁₃In₉/CNTs. This work highlights the importance of charge deficiency of single-atom Pt catalysts for designing high-performance MOR catalysts.