Engineering intrinsic defects in CuO NWs through laser irradiation: Oxygen vs copper vacancies

Defect engineering in CuO nanomaterials has been extensively investigated because this technology can greatly improve the performance of CuO components in a variety of applications. While many previous studies have focused on the role of oxygen vacancies, (VO), in CuO, little attention has been paid to that of copper vacancy centers, (VCu), since the presence of these defects is often difficult to quantify. As a result, the specific roles played by these different vacancy centers on the measured properties of CuO have not been studied systematically. In this article, we show that the concentration of both VO and VCu centers can be engineered in CuO NWs through nanosecond (ns) laser irradiation. The identification of these vacancies was achieved through X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Absorption spectra and diffuse reflectance spectra of laserprocessed samples show that increasing the concentration of VO centers enhances the optical absorption of CuO in the visible region. Data obtained from Mott-Schottky and Nyquist plots, together with measured I-V characteristics, show that laser-induced VCu centers can enhance the carrier concentration in CuO NWs. These data, in addition to O 1s XPS spectra on laser-processed and unprocessed samples as well as cyclic voltammetry, also indicate that laser irradiation can significantly enhance surface adsorption for applications in photoelectrochemistry and electrochemistry. To demonstrate the efficacy of this laser irradiation technique for potential electrochemistry applications, the role of laser-induced VCu and VO defect centers in CuO NWs on the nonenzymatic sensing of glucose has also been investigated. We find that the introduction of VO centers in CuO NWs enhances the current response for glucose sensing while the presence of VCu centers inhibits this response.

Automated summary

Defect engineering in CuO nanomaterials, particularly the control of oxygen vacancies (VO) and copper vacancy centers (VCu), has been studied for their impact on CuO properties. Increasing the concentration of VO enhances optical absorption in the visible region, while laser-induced VCu centers increase carrier concentration in CuO.