# Unraveling Surface Reconstruction of MOF‐Derived La, P‐Co3O4 for Energy‐Efficient Water and Urea Electrolysis

## TL;DR

This paper introduces a new catalyst that improves water and urea electrolysis by reconstructing its surface during reactions, leading to better performance and energy savings.

## Contribution

The study introduces a novel La, P-doped Co3O4 catalyst that enables early surface reconstruction and enhanced electrocatalytic performance for energy-efficient water and urea electrolysis.

## Key findings

- La, P-Co3O4 exhibits low overpotentials of 351 mV for OER, 222 mV for HER, and 1.46 V for UOR at 50 mA cm−2.
- The catalyst achieves 19.4% energy savings in urea electrolysis compared to water electrolysis while maintaining stability for 72 hours.
- Surface reconstruction into γ-CoOOH occurs earlier in La, P-Co3O4 during the OER process, enhancing catalytic activity.

## Abstract

Constructing robust electrocatalysts and shedding light on the processes of surface reconstruction is crucial for sustained hydrogen production and a deeper understanding of catalytic behavior. Here, a novel ZIF‐67‐derived lanthanum‐ and phosphorus‐co‐doped Co3O4 catalyst (La, P‐Co3O4) has been reported. X‐ray absorption spectroscopy (XAS) confirms that the La and P co‐doping reduces the coordination number (CN), improves oxygen vacancies (Ov), and leads to lattice distortion. Soft XAS confirms that Co2+ exists predominantly in La, P‐Co3O4 than in Co3O4. Investigation of surface reconstruction with in situ Raman spectroscopy, revealing that La, P‐Co3O4 reconstructs earlier into catalytically active γ‐CoOOH during the oxygen evolution reaction (OER) process. As a result, La, P‐Co3O4 exhibits commendable electrocatalytic performance with minimal overpotentials of 351 mV for the OER, 222 mV for the hydrogen evolution reaction (HER), and 1.46 V for the urea oxidation reaction (UOR) to achieve a current density of 50 mA cm−2. A two‐electrode electrolyzer using La, P‐Co3O4 as anode and cathode, achieving 19.4% energy savings during urea electrolysis compared to overall water electrolysis while maintaining stability for 72 h. This study provides a new perspective for understanding the mechanism and co‐doping impact on the physicochemical properties of spinel Co3O4 for sustainable energy conversion.

Enhanced OER by surface reconstruction: The dopant promotes surface reconstruction and surface oxygen vacancies, which enhance electrochemical activity, charge transfer, and stability, resulting in improved water and urea electrolysis.