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Employing a facile one-pot hydrothermal synthesis approach, in this work, we achieved the successful synthesis of a CuCoO2/CuO heterostructure, which was characterized by an atomic-scale intimately bonded interface. This can be utilized as a reference for the synthesis of heterostructures involving multiple compounds and their secondary phases. Notably, the CuCoO2/CuO heterostructure stands out for its superior performance in photocatalytic overall water splitting without relying on additional co-catalysts or sacrificial agents. In addition, this heterostructure displayed excellent electrocatalytic activity, photocatalytic activity for the degradation of trichloromethane, and promising PEC performance when utilized as a photocathode. A pivotal feature of the CuCoO2/CuO heterostructure is its capacity to efficiently inhibit the migration of photogenerated holes from CuCoO2 to CuO. This was attributed to the synergistic effects between the intrinsic interface electric field and pronounced valence band offset. Interestingly, this mechanism overcomes the traditional limitations associated with type-I heterostructures. Consequently, the two half-reactions of the overall water splitting process are selectively localized on opposite facets of the CuCoO2/CuO heterostructure. Overall, our findings elucidate the profound implications of band alignment in these heterostructures, offering pivotal insights for the innovation and optimization of advanced heterostructure photo(electro)catalytic materials. [ABSTRACT FROM AUTHOR]

The exploration of novel photocatalyst is one of the important directions of developing efficient photocatalysis technology. Delafossite CuCoO2 has unique crystal structure, suitable band gap and energy band edge, and excellent catalytic activity, which is a new photocatalyst well worth developing. However, the as-prepared CuCoO2 samples in literature often have the problems of containing impurity or secondary phases, non-stoichiometry, leading to some controversies about its fundamental physicochemical properties. Moreover, there is also insufficient understanding of the use of CuCoO2 as a novel photocatalyst. Herein, one-pot hydrothermal method was used to prepare stoichiometric delafossite CuCoO2 microcrystals (~ 3.65 μm) with high purity and single-phase. Then, its detailed fundamental physicochemical properties as photocatalyst are further provided by a series of experimental characterization and density functional theory calculations. The results show that delafossite CuCoO2 exhibit outstanding semi-metallic ferromagnetism, multiple electron transitions caused by various band gap types, multi band absorption and full spectrum absorption, and has appropriate band edge position, which can be applied to HER and OER of water splitting. The photocatalytic performance of CuCoO2 was systematically tested for the first time by photocatalytic degradation of tetracycline hydrochloride, photocatalytic water-splitting, and photocurrent measurement in PEC cell. Under visible light irradiation, the as-prepared CuCoO2 can degrade more than 90% of tetracycline hydrochloride within 4 h. Without sacrificial agent and cocatalyst, the shows the hydrogen and oxygen evolution rates from photocatalytic water-splitting of as-prepared CuCoO2 reached to 2.60 and 128.53 μmol/h g, respectively. In the three-electrode electrochemical cell with 1 M Na2SO4 electrolyte and zero-bias, the photocurrent density of CuCoO2 based photocathode reached to 20 μA/cm2. These findings prove that CuCoO2 has obvious advantages and great potential as a visible-light-driven photocatalyst. [ABSTRACT FROM AUTHOR]

The current low conversion efficiency of Cu2ZnSnS4 (CZTS)‐based thin film solar cells is mainly blamed on the high carrier recombination via interface states at the absorber‐buffer. In this work, ZnO1−xSx solid solution is exploited as the potential buffer layer materials to solve this issue by using density functional theory calculations. With the varying of solid solubility, the lattice constant of ZnO1−xSx solid solution follows the first‐order Vegard's Law, while its bandgap follows the second‐order Vegard's Law. Based on the systematical analysis of crystal structure and electronic properties of ZnO1−xSx solid solution, ZnO0.375S0.625 is screened as the optimal buffer layer material for CZTS‐based thin film solar cells, owing to the suitable bandgap (2.33 eV) and the smallest lattice mismatch (<7%). The CZTS/ZnO0.375S0.625 interface has less harmful interface state, small conduction band offset (−0.02 eV) and band bending (−0.23 eV). Moreover, its band alignment belongs to the staggered Type‐II heterojunction, and its built‐in electric field is in the same direction as the carrier migration, which is very favorable for the efficient separation and fast transfer of photogenerated carriers. Therefore, these interface features and effects of CZTS/ZnO0.375S0.625 heterojunction can significantly boost the photovoltaic performance of CZTS‐based thin film solar cells. [ABSTRACT FROM AUTHOR]

Degenerate semiconductors have many unique electronic structures and optical properties which give them the potential to produce localized surface plasmon resonance (LSPR). Non-stoichiometric Cu2−xS compounds have attracted much interest as photocatalysts. What kind of interesting phenomena will occur when the above aspects are combined? In order to examine this idea, in the present work the LSPR effects of Cu2−xS compounds as degenerate semiconductors and their application in the field of photocatalysis were systematically studied by combining density functional theory calculations, finite-difference time-domain simulations, and experimental preparation and characteristics. It was confirmed that the non-stoichiometric Cu2−xS compound is a typical degenerate semiconductor. The degenerate states of Cu2−xS directly lead to LSPR effects, which can be controlled by the non-stoichiometry and particle size of the Cu2−xS compounds. The enhanced photocatalytic activity of the LSPR effects was evaluated by degrading organic pollutants, revealing that LSPR effects can enable Cu2−xS to achieve photocatalytic degradation of organic pollutants driven by full-spectral irradiation. These findings suggest that further research and development on degenerate semiconductors as novel photocatalysts is worthwhile. [ABSTRACT FROM AUTHOR]

The preparation, X-ray crystallography, EPR, magnetic and luminescent investigation of new metal-anion radical framework materials based on a new anion radical ligand generated by in situdeprotonation of a stable zwitterionic radical are described herein. N,O,N-tripodal anion radical ligand (bipo−) links metal cations, giving rise to four isostructural one-dimensional metal–organic frameworks, [M(bipo−)(L)]n[M = Zn, L = HCOO−(1), SCN−(1a), N3−(1b); M = Co, L = Br−(3)]. The tripodal bipo− ligand and one co-ligand, 1,4-benzenedicarboxylate, coordinate to metals leading to two isostructural two-dimensional metal–organic frameworks, [M(bipo−)(BDC)0.5]n[M = Zn (2) and Co (4)]. The two CoIIcompounds are the first examples that exhibit unusual ferromagnetic to antiferromagnetic phase transition with transition temperature over room temperature, which can be demonstrated by the cooling and warming measurements of susceptibility. Compound 4also exhibits long-range magnetic ordering with the critical temperature at about 44 K proved by ac susceptibility measurements. The metal-radical frameworks exhibit distinctly different fluorescence emissions. Especially, the isomorphous one-dimensional ZnIIcompounds show interesting terminal anion ligand-induced photoluminescent color changes, including direct and invariable white-light-emission with terminal SCN−ligand. [ABSTRACT FROM AUTHOR]