# Synergistic Enhancement of Ethanol Oxidation on Pd/Ce2Ti2O7–TiO2 via Multiorbital (p–d–f) Interactions

## TL;DR

This paper shows that a new catalyst based on palladium and a cerium-titanate support improves ethanol oxidation in fuel cells and ethanol detection.

## Contribution

The study introduces a novel Pd/Ce2Ti2O7–TiO2 catalyst with enhanced ethanol oxidation activity and durability due to multiorbital interactions.

## Key findings

- Pd/Ce2Ti2O7–TiO2 shows 2.70 and 2.63 times higher mass activity than Pd/TiO2 and Pd/C.
- The catalyst exhibits 18.8% ECSA loss after 1000 cycles, better than Pd/C (33.3%).
- It has a low ethanol detection limit of 12.0 μM for nonenzymatic sensing.

## Abstract

Ethanol oxidation reaction (EOR) is a key component of
direct ethanol
fuel cells (DEFCs). However, due to its slow kinetics, EOR remains
a significant challenge, leading to an increasing search for low-cost,
efficient, and stable catalysts. Herein, palladium (Pd) nanostructured
catalysts supported on titanium dioxide (Pd/TiO2) and cerium
titanate (Pd/Ce2Ti2O7–TiO2) were prepared for EOR. The Pd/Ce2Ti2O7–TiO2 catalyst exhibits superior electroactivity
toward the EOR, demonstrating a high mass activity of 2.70 and 2.63-fold
relative to Pd/TiO2 and Pd/C, respectively. The enhanced
behavior was attributed to the bifunctional mechanism, improved electron
transport, and downshifted d-band center (εd). Density
functional theory (DFT) calculations show a higher density of states
for Pd/Ce2Ti2O7–TiO2,suggesting higher EOR kinetics than the Pd and Pd/TiO2, due to its multiorbital (p–d–f) hybridization. The
accelerated durability test (ADT) reveals that the Pd/Ce2Ti2O7–TiO2 catalyst exhibits
satisfactory durability, showing an electrochemically active surface
area (ECSA) loss of 18.8% compared with the Pd/C catalyst (33.3% loss)
after 1000 cycles. Furthermore, the Pd/Ce2Ti2O7–TiO2 catalyst exhibited a low detection
limit of 12.0 μM toward the nonenzymatic amperometric detection
of ethanol. Thus, this study demonstrates the promising use of Ce2Ti2O7–TiO2 as a support
for Pd-based catalysts for EOR in DEFCs and a nonenzymatic amperometric
sensor.