Opto-Electronic Characterization of Photocatalysts Based on p,n-Junction Ternary and Quaternary Mixed Oxides Semiconductors (Cu2O-In2O3 and Cu2O-In2O3-TiO2)

Davide Michele Stefano Marcolongo,Nicoletta Ditaranto,Roberto Comparelli,Francesco Nocito,Michele Aresta,Angela Dibenedetto

doi:10.3390/catal12020153

Abstract

Semiconductor materials are the basis of electronic devices employed in the communication and media industry. In the present work, we report the synthesis and characterization of mixed metal oxides (MOs) as p,n-junction photocatalysts, and demonstrate the correlation between the preparation technique and the properties of the materials. Solid-state UV-visible diffuse reflectance spectroscopy (UV-VIS DRS) allowed for the determination of the light absorption properties and the optical energy gap. X-ray photoelectron spectroscopy (XPS) allowed for the determination of the surface speciation and composition and for the determination of the valence band edge. The opto-electronic behavior was evaluated measuring the photocurrent generated after absorption of chopped visible light in a 3-electrode cell. Scanning electron microscopy (SEM) measurements allowed for auxiliary characterization of size and morphology, showing the formation of composites for the ternary Cu2O-In2O3 p,n-mixed oxide, and even more for the quaternary Cu2O-In2O3-TiO2 MO. Light absorption spectra and photocurrent-time curves mainly depend upon the composition of MOs, while the optical energy gap and defective absorption tail are closely related to the preparation methodology, time and thermal treatment. Qualitative electronic band structures of semiconductors are also presented.

Highlights

Dipartimento di Chimica, Università degli Studi di Bari Aldo Moro, Via Orabona 4, 70125 Bari, Italy; CIRCC-Interuniversity Consortium on Chemical Reactivity and Catalysis, Via Celso Ulpiani 27, 70126 Bari, Italy
The opto-electronic behavior of the most interesting samples was evaluated measuring the photocurrent generated after the absorption of chopped visible light in a 3-electrode cell
Series 1: microwave assisted hydrothermal (MWA-HT)-In2 O3 prepared by application of a 5, 10 or 15 min heating ramp to reach 120 ◦ C, calcined at 300 or 500 ◦ C for 2 h

Summary

Introduction

Dipartimento di Chimica, Università degli Studi di Bari Aldo Moro, Via Orabona 4, 70125 Bari, Italy; CIRCC-Interuniversity Consortium on Chemical Reactivity and Catalysis, Via Celso Ulpiani 27, 70126 Bari, Italy. CNR-IPCF, Istituto per i Processi Chimico-Fisici, S.S. Bari, c/o Dipartimento di Chimica, Via Orabona 4, Innovative Catalysis for Carbon Recycling-IC2R Ltd., Tecnopolis, 70010 Valenzano, Italy; Abstract: Semiconductor materials are the basis of electronic devices employed in the communication and media industry. Solid-state UV-visible diffuse reflectance spectroscopy (UV-VIS DRS) allowed for the determination of the light absorption properties and the optical energy gap. Light absorption spectra and photocurrent-time curves mainly depend upon the composition of MOs, while the optical energy gap and defective absorption tail are closely related to the preparation methodology, time and thermal treatment. 1. Introduction with regard to jurisdictional claims in Semiconductor materials are the basis of the electronic devices employed in the communication and media industry, deeply influencing relations and culture in the modern era. Semiconductors absorb and emit radiations, matching them with electronic conductivity, that is the basis for energy generation by photovoltaic devices, answering the request for cleaner energy [1]

Methods

Results

Conclusion