Scalable neutral H₂O₂ electrosynthesis by platinum diphosphide nanocrystals by regulating oxygen reduction reaction...

Area of Science:

• Electrocatalysis
• Nanomaterials
• Green Chemistry

Background:

• Current methods for hydrogen peroxide (H2O2) production face limitations in selectivity, stability, and on-site generation.
• Developing efficient and non-toxic electrocatalysts for the oxygen-to-hydrogen peroxide reaction is crucial for sustainable H2O2 synthesis.

Purpose of the Study:

• To report the development of ultrasmall and monodisperse colloidal platinum phosphide (PtP2) nanocrystals as an electrocatalyst for H2O2 production.
• To investigate the catalytic mechanism and assess the performance and stability of PtP2 nanocrystals in a polymer electrolyte membrane fuel cell (PEMFC).

Main Methods:

• Synthesis of ultrasmall, monodisperse colloidal PtP2 nanocrystals.
• Electrocatalytic performance evaluation using rotating ring-disk electrode and PEMFC.
• Density functional theory (DFT) calculations to elucidate the reaction mechanism.
• Atomic layer deposition (ALD) of Al2O3 for catalyst stabilization.

Main Results:

• PtP2 nanocrystals achieved H2O2 production at near zero-overpotential with high selectivity (>99%) at 0.27 V vs. RHE.
• DFT calculations revealed that phosphorus (P) in PtP2 weakens the Pt-OOH* bond, favoring H2O2 formation.
• ALD-coated PtP2 in a PEMFC demonstrated a maximum H2O2 production rate of 2.26 mmol h-1 cm-2 and 78.8% current efficiency at 150 mA cm-2.
• Stable operation enabled accumulation of 3.0 wt% neutral H2O2 solution (pH 6.6) in 600 mL.

Conclusions:

• Ultrasmall PtP2 nanocrystals are highly efficient and selective electrocatalysts for H2O2 production.
• The catalyst's stability and performance in a PEMFC pave the way for continuous, on-site generation of neutral H2O2.
• This work offers a promising pathway towards sustainable and practical H2O2 synthesis.