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The structural, electronic, optical, mechanical, lattice dynamics, and electronic transport properties of SrCu2O2 crystals were studied using first-principles calculations. The calculated band gap of SrCu2O2 using the HSE hybrid functional is about 3.33 eV, which is well consistent with the experimental value. The calculated optical parameters show a relatively strong response to the visible light region for SrCu2O2. The calculated elastic constants and phonon dispersion indicate that SrCu2O2 has strong stability in mechanical and lattice dynamics. The deep analysis of calculated mobilities of electrons and holes with their effective masses proves the high separation and low recombination efficiency of photoinduced carriers in SrCu2O2. [ABSTRACT FROM AUTHOR]

Electronic structure, optical, mechanical, and lattice dynamical properties of the tetragonal MgBi2O6 are studied using a first-principles method. The band gap of MgBi2O6 calculated from the PBE0 hybrid functional method is about 1.62 eV and agrees well with the experimental value. The calculations on elastic constants show that MgBi2O6 exhibits mechanical stability and strong elastic anisotropy. The detailed analysis of calculated optical parameters and effective masses clearly indicate that MgBi2O6 has strong optical response in the visible light region and high separation efficiency of photoinduced electrons and holes. [ABSTRACT FROM AUTHOR]

The pyrochlore-type (Sr 0.6 Bi 0.305) 2 Bi 2 O 7 (SBO) containing Bi3+ and Bi5+ mixed valent states was first investigated as a photocatalyst in our very recent work. To further improve the photocatalytic performance, SBO/TiO 2 heterostructured composites were successfully fabricated using a single-step hydrothermal method. The photocatalytic activity of as-prepared samples was evaluated by the degradation of methylene blue under visible light irradiation and photocatalytic hydrogen generation using water. SBO/TiO 2 composites exhibited remarkably enhanced photocatalytic activity and high stability. The enhancement of photocatalytic performance is attributed to the increase of light absorption and the separation of photogenerated carriers on the interface of SBO/TiO 2 heterostructured composites. • (Sr 0.6 Bi 0.305) 2 Bi 2 O 7 /TiO 2 composites exhibit excellent photocatalytic activity and high stability in photocatalytic removal of MB and hydrogen evolution. • The mechanism of MB photodegradation and photocatalytic generating hydrogen under visible light on (Sr 0.6 Bi 0.305) 2 Bi 2 O 7 /TiO 2 were explored. • The formation of heterojunction should be directly responsible for the enhancement in photocatalytic efficiency of composites. Accelerating the separation efficiency of photoexcited electron-hole pairs with the help of binary heterojunction structure is considered to be a promising approach for significantly enhancing the photocatalytic hydrogen production performance of TiO 2. Providing more (Sr 0.6 Bi 0.305) 2 Bi 2 O 7 (SBO) catalysts to function as active sites of TiO 2 , together with the ability to construct heterojunction structures, is highly desirable for photocatalytic hydrogen evolution and pollutant photodegradation. To achieve this goal, in this work, (Sr 0.6 Bi 0.305) 2 Bi 2 O 7 /P25 (SBO/P25) binary heterojunction catalyst is formed in situ on the TiO 2 surface by a simple one-step hydrothermal method. To evaluate the feasibility of SBO/P25 as a very efficient photocatalyst for degradation of MB and photocatalytic hydrogen evolution, a series of photocatalytic experimental studies were carried out. The experimental result indicated that the existence of heterojunction structure in the SBO/P25 nanocomposites improves the photocatalytic activity of P25. The photocatalytic performance of H 2 evolution from water splitting and MB degradation for an optimal SBO/P25 photocatalyst reached 3.18 mmol g–1 h−1 and 3.42 × 10−2 min−1, respectively, which were 7.40 and 5.26 times higher than those of pure P25, respectively. The significantly improved catalytic capability on SBO/P25 is mainly ascribed to the enhanced visible light absorption and charge transfer in comparison with P25. In addition, SBO/P25 composites have excellent stability and recyclability, showing great potential for application in wastewater treatment and photocatalytic hydrogen evolution. [ABSTRACT FROM AUTHOR]

The pyrochlore-type (Sr0.6Bi0.305)2Bi2O7 (SBO), containing Bi3+ and Bi5+ mixed valent states, was recently found to be used as a new visible light responsive photocatalyst. Novel SBO/SnO2 heterostructured composites were synthesized through a facile one-step hydrothermal method. The phase structure, morphology, chemical composition, and optical properties of the obtained samples were characterized by XRD, SEM, TEM, XPS, and UV-vis DRS. Compared to pure SBO and SnO2, the synthesized SBO/SnO2 composites exhibited significantly enhanced photocatalytic efficiency. The results indicated that the photoinduced holes and superoxide radicals play a dominant role and are the main reactive species during the degradation of Methylene Blue (MB) solution under visible light irradiation. Heterojunctions, formed in samples, directly contribute to the improvement of photocatalytic efficiency of SBO/SnO2 composites, since it not only broadens the light response range, but also accelerates the separation of photogenerated carriers. [ABSTRACT FROM AUTHOR]

[Display omitted] • Heterostructured CaCO 3 /NiS composites were synthesized via the facile hydrothermal method. • CaCO 3 /NiS showed the significantly enhanced photocatalytic bactericidal performance. • The active OH and O 2 – cooperate with vacancies to enhance bactericidal performance of CaCO 3 /NiS. CaCO 3 /NiS heterostructured composites were synthesized via the facile hydrothermal method. CaCO 3 /NiS showed the best photocatalytic bactericidal performance when the addition was 15 mg. Under 10 min visible light irradiation, about 90 % of Staphylococcus aureus was killed by composite, which was 4.5 times and 3 times faster than CaCO 3 and NiS. The addition of CaCO 3 significantly improves the photocurrent response and electron-hole pair separation rate of NiS and effectively increases the yield of active free radical groups. These groups cause the bacterial cell membrane to be destroyed and the internal proteins to be flow out, achieving the effect of killing bacteria. The solitary electron pair in the CaCO 3 /NiS composite absorbs visible light energy, making lots of atoms leave the equilibrium check point and effectively preventing the recombination of photogenerated electrons and holes. The inherent active substances (OH and O 2 –) cooperate with vacancies to enhance bactericidal performance. The design and synthesis of CaCO 3 /NiS composites effectively improve the sterilization effect and its application can be expected. [ABSTRACT FROM AUTHOR]

Herein a novel carbon nitride (CN) homojunction between Co2+, cyanate group spatially co-doped and undoped domain is first designed via the ZIF-67 self-templated doping and polymeric condensation of CN, for efficient photocatalytic H 2 evolution (PHE). The microstructure characterizations on the ZIF-67 amount-dependent crystallinity and modifications confirm the successful construction of CN homojunction between Co2+-concentrated domain and undoped domain (CoCN). As a result, the optimized CoCN shows an improved PHE rate (2512 μmol·g−1·h−1) 2.93 times that of pristine CN, with further 1.7 times increase after 5 rounds of cycling (4305 μmol·g−1·h−1). Steady-transient photoluminescence and photo-electrochemical investigations demonstrate that ZIF-67 self-templated doping enhances visible light absorption and the separation/transfer of photogenerated carriers. Further energy-band analysis suggests that the coupling of the doped and undoped domains facilitates the built-in electric field and band bending, leading to Self-S-Scheme mechanism of photocatalysis. This work provides a new method for the design of CN-based junctions via ZIF-67 templated doping boosting photocatalytic activity. [Display omitted] • g-C 3 N 4 homojunction between Co2+, cyanate doped and non-doped domains is designed via ZIF-67 self-templated doping. • The optimized CoCN shows improved PHE rate (2512 μmol·g-1·h-1), 2.93 times higher than that of pristine CN. • The 40 CoCN exhibits superior stability and improved PHE rate with cycling (to 4305 μmol·g−1·h−1 after 5th cycling). • The Self-S-Scheme mechanism was proposed to explain the superior PHE performance. [ABSTRACT FROM AUTHOR]

The pyrochlore-type (Sr 0.6 Bi 0.305) 2 Bi 2 O 7 containing Bi3+ and Bi5+ mixed valent states was first investigated as a new photocatalytic material in this work and successfully synthesized by using a facile hydrothermal method. Our experimental measurements combining with the first-principles calculations show that (Sr 0.6 Bi 0.305) 2 Bi 2 O 7 is n-type semiconductor with a band gap of 1.25 eV. The as-prepared (Sr 0.6 Bi 0.305) 2 Bi 2 O 7 exhibits high photocatalytic efficiency and stability under visible light irradiation. The calculated electronic density of states indicates that Bi and O atoms close to the Sr vacancy probably possess higher activity and are helpful for its photocatalytic performance. • (Sr 0.6 Bi 0.305) 2 Bi 2 O 7 containing Bi3+ and Bi5+ mixed valent states was first investigated as a new photocatalytic material. • The experimental measurements combining with the first-principles calculations show that (Sr 0.6 Bi 0.305) 2 Bi 2 O 7 is n-type semiconductor with a band gap of 1.25 eV. • (Sr 0.6 Bi 0.305) 2 Bi 2 O 7 exhibits high photocatalytic efficiency and stability under visible light irradiation. • Electronic structure calculations indicate that Bi and O atoms close to the Sr vacancy probably possess higher activity and are helpful for its photocatalytic performance. The pyrochlore-type (Sr 0.6 Bi 0.305) 2 Bi 2 O 7 containing Bi3+ and Bi5+ mixed valent states was first investigated as a new photocatalytic material in this work and successfully synthesized by a facile hydrothermal method. The phase structure, morphology, microstructure, elemental composition, and optical properties of samples were characterized in details. The experimental measurements combining with the first-principles calculations show that (Sr 0.6 Bi 0.305) 2 Bi 2 O 7 is a n-type semiconductor with a band gap of 1.25 eV. The photocatalytic activity of (Sr 0.6 Bi 0.305) 2 Bi 2 O 7 was evaluated by the degradation of various organic dyes. Our results show that (Sr 0.6 Bi 0.305) 2 Bi 2 O 7 exhibits high photocatalytic efficiency and stability under visible light irradiation. The calculated electronic density of states indicates that Bi and O atoms close to the Sr vacancy probably possess higher activity and are helpful for its photocatalytic performance. [ABSTRACT FROM AUTHOR]