Understanding the Role of Copper Vacancies in Photoelectrochemical CO2 Reduction on Cuprous Oxide

The impact of intrinsic point defects on the optoelectronic functionality of CuGaO2: insights from first-principles calculations

The conversion of light energy into electrical or chemical energy is essential for sustainable development and clean energy applications, making optoelectronic functional technology a critical field of study. Among optoelectronic materials, delafossite CuGaO2 stands out due to its unique p-type conductivity and optoelectronic characteristics. However, the effect of intrinsic point defects within its lattice structure on the optoelectronic performance remains not fully comprehended. This study presents a systematic analysis of the thermodynamic stability, electronic structure, and optical properties of intrinsic point defects in CuGaO2, and their impact on optoelectronic functionality, utilizing first-principles calculations. The findings reveal that copper vacancies (VCu), copper-gallium antisites (CuGa), and interstitial oxygen (Oi) are the predominant intrinsic point defects. These defects introduce new energy levels within the bandgap, significantly enhancing the light absorption spectrum and, consequently, the optoelectronic performance of CuGaO2. This research extends prior studies by identifying the types and concentrations of intrinsic point defects in CuGaO2 and their regulatory effect on optoelectronic performance, and by proposing novel strategies for the design and optimization of CuGaO2-based optoelectronic materials. The results are significant for advancing the understanding of CuGaO2 and providing valuable insights for defect engineering in other optoelectronic materials. This study underscores the significance of precise control over intrinsic point defects at the atomic level for the development of high-performance optoelectronic materials, thus opening new avenues for the advancement of future optoelectronic technologies.

Efficient Photoelectrochemical Reduction of CO2 in Seawater with Cheap and Abundant Cu2O/Al2O3/TiO2 Electrode

The photoelectrochemical (PEC) reduction of carbon dioxide to environmentally friendly fuels is a promising strategy to address the challenge of clean energy demand. Semiconductor photocathodes such as Cu2O enable the reduction of carbon dioxide, but their main drawback is their instability and susceptibility to photocorrosion. In this work, Al2O3 and TiO2 were utilized to enhance stability, photoelectrochemical activity, and charge transport facilitation, resulting in a 2.8-fold increase in generated photocurrent density (1.4 mA/cm2 at -0.2 V vs. RHE). The experiments were conducted in a 0.5 M NaCl solution, simulating seawater conditions, to evaluate the performance and stability of the system in an environment closer to real-world applications.

Crystal Facet Dependent Energy Band Structures of Polyhedral Cu2O Nanocrystals and Their Application in Solar Fuel Production

We demonstrated a facile hydrothermal method to synthesize the (100)-, (110)- and (111)-oriented Cu₂O nanocrystals (NCs) by controlling the concentration of the incorporated anions (CO₃^2- and SO₃^2-). The crystal facet dependent activity of the orientation controlled Cu₂O NCs in the rhodamine B (RhB) photodegradation and photocatalytic hydrogen (H₂) evolution was found to follow the trend: (111) > (110) > (100). The mechanism was investigated by characterizing the optical property, energy band structure, interfacial charge carrier dynamics and reducing ability. The results indicated that the (111)-oriented Cu₂O NCs exhibit the higher conduction band (CB) potential as compared with the (110)-oriented and (100)-oriented Cu₂O NCs, which resulted in the largest driving force of interfacial electron transfer for (111)-oriented Cu₂O NCs to carry out solar fuel generation. The current study offers an easy strategy for crystal facet engineering of semiconductors and provides important physical insights into their electronic properties for the desired solar energy conversions.