# Enhancing Cascade Reaction Efficiency by Local pH Regulation for Integrated Anodic H2O2 Generation and Ammoximation

## TL;DR

This paper presents a method to efficiently produce oximes by combining electrochemical H2O2 generation with ammoximation, using local pH control to enhance reaction efficiency.

## Contribution

The study introduces a pH-regulated cascade system that couples H2O2 electrogeneration with ammoximation, achieving high electron efficiency and H2O2 utilization.

## Key findings

- An FTO/Sb2WO6 anode achieved 87% Faradaic efficiency for H2O2 production.
- Cyclohexanone oxime was synthesized with 99% selectivity and 81% electron efficiency.
- Local pH regulation suppressed side reactions and improved cascade selectivity.

## Abstract

Cascade reaction strategies integrating electrochemistry with chemical transformations offer routes for the synthesis of value‐added chemicals. However, the efficiencies of such integrated processes get compromised due to competitive electrochemical reactions and incompatibility between electrochemical and chemical transformations. We report an integrated electrochemical–chemical coupling of anodic H2O2 generation with ammoximation for oxime synthesis. An FTO/Sb2WO6 anode was designed and optimized to anodically produce H2O2 with a maximum Faradaic efficiency (FE) of 87%. H2O2 from the anode oxidizes NH3 to NH2OH, which subsequently reacts with cyclohexanone to yield cyclohexanone oxime with 99% selectivity and a maximum electron efficiency (EE) of 81%. Continuous and adjustable H2O2 input ensures synchronization with the ammonia oxidation reaction while minimizing over‐oxidation of the reaction intermediates. Operando scanning electrochemical microscopy (SECM) revealed local pH shifts caused by the proton‐coupled electron transfer and its effect on the FE of H2O2 synthesis and competing NH3 oxidation, providing mechanistic insights for optimizing the reaction microenvironment. By regulating the electrolyte composition to modulate the interfacial pH, side reactions were suppressed and H2O2 generation was promoted, thereby enhancing cascade selectivity. This work highlights local pH regulation as a tool to improve reaction compatibility and efficiency in cascade electrosynthesis.

This work integrates anodic H2O2 generation with ammoximation for efficient oxime synthesis. By regulating the local pH through electrolyte engineering, the system achieves 81% electron efficiency (EE) and 98% H2O2 utilization, offering a generalizable strategy for cascade electrochemical–chemical processes.