Boosting the activity of Prussian-blue analogue as efficient electrocatalyst for water and urea oxidation

Xiao Wang,Koji Kajiyoshi,Peipei Dong,Chunru Wang,Jianfeng Huang,Li Feng,Liangliang Feng,Liyun Cao,Yongqiang Feng,Jie Li

doi:10.1038/s41598-019-52412-1

Abstract

The design and fabrication of intricate hollow architectures as cost-effective and dual-function electrocatalyst for water and urea electrolysis is of vital importance to the energy and environment issues. Herein, a facile solvothermal strategy for construction of Prussian-blue analogue (PBA) hollow cages with an open framework was developed. The as-obtained CoFe and NiFe hollow cages (CFHC and NFHC) can be directly utilized as electrocatalysts towards oxygen evolution reaction (OER) and urea oxidation reaction (UOR) with superior catalytic performance (lower electrolysis potential, faster reaction kinetics and long-term durability) compared to their parent solid precursors (CFC and NFC) and even the commercial noble metal-based catalyst. Impressively, to drive a current density of 10 mA cm−2 in alkaline solution, the CFHC catalyst required an overpotential of merely 330 mV, 21.99% lower than that of the solid CFC precursor (423 mV) at the same condition. Meanwhile, the NFHC catalyst could deliver a current density as high as 100 mA cm−2 for the urea oxidation electrolysis at a potential of only 1.40 V, 24.32% lower than that of the solid NFC precursor (1.85 V). This work provides a new platform to construct intricate hollow structures as promising nano-materials for the application in energy conversion and storage.

Highlights

The design and fabrication of intricate hollow architectures as cost-effective and dual-function electrocatalyst for water and urea electrolysis is of vital importance to the energy and environment issues
High-resolution TEM (HRTEM) acquired from the individual cage marked in Fig. 1d demonstrated a crystal lattice fringe spacing of 0.512 nm corresponding to the (200) plane as evidenced in Fig. 1e, which was in good agreement with the typical face-centered cubic Prussian-blue analogue (PBA) crystal phase[45]
It was worth noting that a combination analysis of the high-angle annular dark field TEM (HAADF-TEM) image and the elemental mapping suggested that the N and O were mainly distributed on the inner and outer surface of Co-Fe hollow cage (CFHC), which could be ascribed to the adsorption of the hydrophilic PVP molecules on the cage (Fig. 1d and Supplementary Fig. S4) during the solvothermal reaction

Summary

Introduction

The design and fabrication of intricate hollow architectures as cost-effective and dual-function electrocatalyst for water and urea electrolysis is of vital importance to the energy and environment issues. The as-obtained CoFe and NiFe hollow cages (CFHC and NFHC) can be directly utilized as electrocatalysts towards oxygen evolution reaction (OER) and urea oxidation reaction (UOR) with superior catalytic performance (lower electrolysis potential, faster reaction kinetics and long-term durability) compared to their parent solid precursors (CFC and NFC) and even the commercial noble metal-based catalyst. The in-situ released proton from the ethanol solvent induced the structure evolution accompanied with a metal-metal electron transfer (CoП-CN-FeШ → CoШ-CN-FeП) This strategy was applicable to Ni-Fe PBA cube (NFC) to construct Ni-Fe hollow cage (NFHC). Our work show the feasibility and diversity of template-engaged synthesis of hollow architectures as efficient electrocatalysts, which would shed new light on the design and fabrication of novel promising catalysts with intricate hollow structures to promote the hydrogen production. The present method can pave the way for the construction of novel nano-materials in the realms of energy conversion and storage, such as fuel cells, lithium-ion batteries (LIBs), supercapacitors, etc

Methods

Results

Conclusion