# Ni Single‐Atom Modulation of Ti‐O Covalency Boosts Ammonia Oxidation Electrocatalysis

## TL;DR

Adding nickel single atoms to titanium dioxide boosts its ability to efficiently and durably convert ammonia into nitrogen gas.

## Contribution

A new strategy using nickel single atoms to modulate Ti-O covalency in TiO2 for enhanced ammonia oxidation electrocatalysis.

## Key findings

- Ni SAC@TiO2 nearly doubles the catalytic activity of pristine TiO2 for ammonia oxidation.
- The catalyst retains over 98% performance after 2000 accelerated stress testing cycles.
- The strategy suppresses NOx formation and promotes selective N2 evolution via NHx-NHy coupling.

## Abstract

Non‐noble transition metal oxides, particularly TiO2‐based systems, can be an alternative to noble metal‐based catalysts for the electrochemical ammonia oxidation reaction (AOR) due to their abundance, low cost, and corrosion resistance, but it remains hindered by lower performance and undesired selectivity toward oxygenated nitrogen species instead of N2, largely stemming from insufficient active sites and higher energy barrier for coupling intermediates. To overcome the issues, we introduce a Ni single‐atom‐induced covalent modulation strategy for constructing Ni SAC@TiO2 with tunable Ti‐O covalency. Hard and soft X‐ray absorption (XAS) combined with photoelectron spectroscopy (XPS) reveal strong metal‐support interactions that enhance Ti‐O covalency and create abundant active sites. Ni SAC@TiO2 catalyst nearly doubles the catalytic activity of pristine TiO2 and retains >98% of its initial performance after 2000 accelerated stress testing cycles. In situ surface‐enhanced Raman scattering (SERS) shows improved interaction with reactants and intermediates, while in situ attenuated total reflection‐surface enhanced infrared absorption spectroscopy (ATR‐SEIRAS) demonstrates that Ni SAC@TiO2 effectively suppresses the buildup of deactivating NO
x
species and promotes NH
x
‐NH
y
coupling mediated pathways for selective N2 evolution, further corroborating the theoretical insights. These findings highlight single‐atom modulation of Ti‐O covalency as a powerful strategy to unlock efficient and robust TiO2‐based catalysts for AOR.

A Ni single‐atom‐induced enhancement of Ti‐O covalency in Ni SAC@TiO2 generates abundant active sites and promotes selective NH
x
‐NH
y
mediated N2 evolution while suppressing poisonous NO
x
formation, achieving nearly doubled AOR activity with excellent durability.