Copper(I)-Based p-Type Oxides for Photoelectrochemical and Photovoltaic Solar Energy Conversion

Abstract

Recent research efforts have been growing into p-type copper­(I) based oxides for development of their use in solar energy applications. The oxides of interest include the binary Cu2O and a number of new ternary Cu x M y O z oxides. Both the binary and ternary Cu­(I)-based oxides have many advantages when compared to other well-known p-type oxides such as NiO, III–V, and II–VI semiconductors. The benefits found within the diverse group of Cu­(I)-containing oxides include bandgap sizes that can be tuned from ∼1.2 to >3.0 eV, high charge carrier mobility, and favorable band energies relative to fuel-producing redox couples. These properties give them potential utility in a variety of different solar applications, such as in dye-sensitized solar cells and suspended powder photocatalysis. Research efforts into surface modifications and changes in their chemical compositions and structures have allowed for greater stability and greater efficiency in aqueous solutions, both of which have represented two key barriers for this class of materials. Presented in this review are the currently known binary and ternary Cu­(I)-oxides and relationships of their syntheses and structures with their visible-light and ultraviolet bandgap sizes, band energies, and photoelectrochemical properties. As their constituent elements are relatively abundant and nontoxic, they represent an attractive class of materials that can be used in the conversion of sunlight to electricity or solar fuels.

Semiconductor‐Based Photoelectrochemical Conversion of Carbon Dioxide: Stepping Towards Artificial Photosynthesis

“…Owing to excitation from the 3 d 10 VB to the primary 4 s CB, copper is prone to suffer from self‐reduction. As a result, adding another metal with unfilled d orbitals will suppress self‐reduction by transferring excited electrons to an early transition state in the CB …”

“…As ar esult, adding another metal with unfilled do rbitals will suppresss elf-reduction by transferring excited electrons to an early transition state in the CB. [58] Electrodeposition from CuSO 4 and Cu (NO 3 ) 2 can lead to pand n-type Cu 2 Ot hin films on Cu foil, respectively.B ae tal. experimented with the two types of electrodes, which demonstrated much higherC O 2 conversion efficiency over the Cu/p-Cu 2 Oe lectrode, especially in the conversion to C 2 H 4 .…”

Low‐Temperature Solution‐Processed CuCrO2 Hole‐Transporting Layer for Efficient and Photostable Perovskite Solar Cells

“…[45] This suggests that the presence of oxygen vacancies in the as-prepared CuCrO 2 sample might result in a slightly imbalanced stoichiometric composition of CuCrO 2 . [46][47][48] To examine the morphology of the prepared CuCrO 2 nanocrystals, TEM, high-resolution TEM (HRTEM), and SAED characterizations were then performed. Such deficiencies indeed induce the generation of holes in the lattices and thus endow the as-prepared CuCrO 2 nanocrystals with p-type semiconducting property.…”

Polymorphism and Structural Distortions of Mixed-Metal Oxide Photocatalysts Constructed with α-U3O8 Types of Layers

“…This is not limited to the space charge width alone, which is composed of the accumulation layer, depletion layers, and inversion layer. The carrier diffusion lengths, and charge carrier mobility are also critical to the material's photocatalytic performance [85,[92][93][94][95]. In addition, selecting a suitable doping strategy is essential to enhancing photocatalytic properties [96].…”

“…The Maggard group has extensively investigated the visible and ultraviolet photocatalytic activity of members from the A m+ ((n+1)/m) B (3n+1) O (8n+3) (e.g., A = Na, Ag, Cu, Pb, Bi; B = Nb, Ta) family of structures as both suspended particles and polycrystalline films for water splitting [92,116,120,121]. Improved charge separation and photocatalytic/photoelectrochemical redox reactions have been proposed to be enhanced in these structures due to the preferential anisotropic diffusion of charge carriers along the BO 7 pentagonal bipyramid layers.…”