Metastable CoCu$_2$O$_3$ for molecular sensing and catalysis

TL;DR

This paper demonstrates a scalable method to produce metastable CoCu₂O₃ nanostructures at room temperature, which exhibit exceptional sensing and catalytic properties for air pollutants, expanding possibilities for novel functional materials.

Contribution

It introduces a non-equilibrium combustion-aerosol process to stabilize metastable metal oxides, enabling control over crystal size and composition for enhanced applications.

Findings

Metastable CoCu₂O₃ can be stabilized at room temperature.

The material shows high sensitivity for benzene detection.

The approach is scalable and applicable to other complex oxides.

Abstract

Metastable nanostructures are kinetically trapped in local energy minima featuring intriguing surface and material properties. To unleash their potential, there is a need for non-equilibrium processes capable of stabilizing a large range of crystal phases outside thermodynamic equilibrium conditions by closely and flexibly controlling atomic reactant composition, spatial temperature distribution and residence time. Here, we demonstrate the capture of metastable pseudo-binary metal oxides at room temperature with scalable combustion-aerosol processes. By a combination of X-ray diffraction, electron microscopy and online flame characterization, we investigate the occurrence of metastable CoCu$_2$O$_3$ with controlled crystal size (4-16 nm) over thermodynamically stable CuO and Co$_3$O$_4$. Immediate practical impact is demonstrated by exceptional sensing and catalytic performance for air pollutant detection (e.g., 15 parts-per-billion benzene). This approach can be extended to various binary, ternary and high entropy oxides with even more components to access novel materials also promising for actuators, energy storage or solar cells.