Copper Nanowires: A Substitute for Noble Metals to Enhance Photocatalytic H₂ Generation

Microwave-assisted hydrothermal approach was developed as a general strategy to decorate copper nanowires (CuNWs) with nanorods (NRs) or nanoparticles (NPs) of metal oxides, metal sulfides, and metal organic frameworks (MOFs). The microwave irradiation induced local “super hot” dots generated on the CuNWs surface, which initiated the adsorption and chemical reactions of the metal ions, accompanied by the growth and assembly of NPs building blocks along the metal nanowires’ surfaces. This solution-processed approach enables the NRs (NPs) @CuNWs hybrid structure to exhibit three unique characteristics: (1) high coverage density of NRs (NPs) per NWs with the morphology of NRs (NPs) directly growing from the CuNWs core, (2) intimate contact between CuNWs and NRs (NPs), and (3) flexible choices of material composition. Such hybrid structures also increased light absorption by light scattering. In general, the TiO₂/CuNWs showed excellent photocatalytic activity for H₂ generation. The corresponding hydrogen production rate is 5104 μmol h^–1 g^–1 with an apparent quantum yield (AQY) of 17.2%, a remarkably high AQY among the noble-metal free TiO₂ photocatalysts. Such performance may be associated with the favorable geometry of the hybrid system, which is characterized by a large contact area between the photoactive materials (TiO₂) and the H₂ evolution cocatalyst (Cu), the fast and short diffusion paths of photogenerated electrons transferring from the TiO₂ to the CuNWs. This study not only shows a possibility for the utilization of low cost copper nanowires as a substitute for noble metals in enhanced solar photocatalytic H₂ generation but also exhibits a general strategy for fabricating other highly active H₂ production photocatalysts by a facile microwave-assisted solution approach

C₆₀-Decorated CdS/TiO₂ Mesoporous Architectures with Enhanced Photostability and Photocatalytic Activity for H₂ Evolution

Fullerene (C₆₀) enhanced mesoporous CdS/TiO₂ architectures were fabricated by an evaporation induced self-assembly route together with an ion-exchanged method. C₆₀ clusters were incorporated into the pore wall of mesoporous CdS/TiO₂ with the formation of C₆₀ enhanced CdS/TiO₂ hybrid architectures, for achieving the enhanced photostability and photocatalytic activity in H₂ evolution under visible-light irradiation. Such greatly enhanced photocatalytic performance and photostability could be due to the strong combination and heterojunctions between C₆₀ and CdS/TiO₂. The as-formed C₆₀ cluster protection layers in the CdS/TiO₂ framework not only improve the light absorption capability, but also greatly accelerated the photogenerated electron transfer to C₆₀ clusters for H₂ evolution

S‑Scheme Photocatalyst NH₂–UiO-66/CuZnS with Enhanced Photothermal-Assisted CO₂ Reduction Performances

Green and mild sunlight-driven photocatalysis has emerged as a promising technology for mitigating climate- and energy-related issues. In CO2 reduction reactions, metal–organic framework (MOF) materials are often compounded with inorganic semiconductor ZnS to form S-scheme photocatalysts that facilitate effective charge migration and separation across the composite interface. However, the large bandwidth of unmodified or modified ZnS remains a major hurdle in achieving efficient photocatalytic reactions. Therefore, this study aimed to reduce the band gap width of ZnS by incorporating Cu-doped ZnS(en)0.5 (CuZnS) as the inorganic semiconductor substrate and NH2–UiO-66 as the organometallic framework material to prepare NH2–UiO-66/CuZnS composite photocatalysts, ultimately realizing a thermally assisted photocatalytic CO2 reduction reaction. With the help of photothermal conversion from CuZnS, the temperature of CO2 reduction increased to 54.2 °C, resulting in a fast kinetic showing an improved yield of 22.85 μmol g–1 h–1 via the photocatalytic route

Highly Efficient and Stable Au/CeO₂–TiO₂ Photocatalyst for Nitric Oxide Abatement: Potential Application in Flue Gas Treatment

In the present work, highly efficient and stable Au/CeO₂–TiO₂ photocatalysts were prepared by a microwave-assisted solution approach. The Au/CeO₂–TiO₂ composites with optimal molar ratio of Au/Ce/Ti of 0.004:0.1:1 delivered a remarkably high and stable NO conversion rate of 85% in a continuous flow reactor system under simulated solar light irradiation, which far exceeded the rate of 48% over pure TiO₂. The tiny Au nanocrystals (∼1.1 nm) were well stabilized by CeO₂ via strong metal–support bonding even it was subjected to calcinations at 550 °C for 6 h. These Au nanocrystals served as the very active sites for activating the molecule of nitric oxide and reducing the transmission time of the photogenerated electrons to accelerate O₂ transforming to reactive oxygen species. Moreover, the Au–Ce³⁺ interface formed and served as an anchoring site of O₂ molecule. Then more adsorbed oxygen could react with photogenerated electrons on TiO₂ surfaces to produce more superoxide radicals for NO oxidation, resulting in the improved efficiency. Meanwhile, O₂ was also captured at the Au/TiO₂ perimeter site and the NO molecules on TiO₂ sites were initially delivered to the active perimeter site via diffusion on the TiO₂ surface, where they assisted O–O bond dissociation and reacted with oxygen at these perimeter sites. Therefore, these finite Au nanocrystals can consecutively expose active sites for oxidizing NO. These synergistic effects created an efficient and stable system for breaking down NO pollutants. Furthermore, the excellent antisintering property of the catalyst will allow them for the potential application in photocatalytic treatment of high-temperature flue gas from power plant

Hierarchical Nanostructured WO₃ with Biomimetic Proton Channels and Mixed Ionic-Electronic Conductivity for Electrochemical Energy Storage

Protein channels in biologic systems can effectively transport ions such as proton (H⁺), sodium (Na⁺), and calcium (Ca⁺) ions. However, none of such channels is able to conduct electrons. Inspired by the biologic proton channels, we report a novel hierarchical nanostructured hydrous hexagonal WO₃ (<i>h</i>-WO₃) which can conduct both protons and electrons. This mixed protonic–electronic conductor (MPEC) can be synthesized by a facile single-step hydrothermal reaction at low temperature, which results in a three-dimensional nanostructure self-assembled from <i>h</i>-WO₃ nanorods. Such a unique <i>h</i>-WO₃ contains biomimetic proton channels where single-file water chains embedded within the electron-conducting matrix, which is critical for fast electrokinetics. The mixed conductivities, high redox capacitance, and structural robustness afford the <i>h</i>-WO₃ with unprecedented electrochemical performance, including high capacitance, fast charge/discharge capability, and very long cycling life (>50 000 cycles without capacitance decay), thus providing a new platform for a broad range of applications