Single-atom catalysts anchoring offers a desirable pathway for efficiency maximization and cost-saving for photocatalytic hydrogen evolution. However, the single-atoms loading amount is always within 0.5% in most of the reported due to the agglomeration at higher loading concentrations. In this work, the highly dispersed and large loading amount (>1 wt%) of copper single-atoms were achieved on TiO2, exhibiting the H2 evolution rate of 101.7 mmol g−1 h−1 under simulated solar light irradiation, which is higher than other photocatalysts reported, in addition to the excellent stability as proved after storing 380 days. More importantly, it exhibits an apparent quantum efficiency of 56% at 365 nm, a significant breakthrough in this field. The highly dispersed and large amount of Cu single-atoms incorporation on TiO2 enables the efficient electron transfer via Cu2+-Cu+ process. The present approach paves the way to design advanced materials for remarkable photocatalytic activity and durability.
High
activity, high stability, and low cost have always been the
pursuit of photocatalyst design and development. Herein, a simple
method is used to integrate abundant anion vacancies (VS) and cation vacancies (VZn) on the surface of ZnS (M–ZnS),
deriving VS and VZn pairs (vacancy pairs), isolated
Zn atoms (Zniso), and isolated S atoms (Siso). Abundant surface vacancy defects fully expose and activate the
surface atoms, regulate the band structure, and significantly improve
the separation of photogenerated carriers. M–ZnS is endowed
with high activity, and the average hydrogen production rate of the
optimal sample increases to 576.07 μmol·g–1·h–1 (λ > 400 nm). Theoretical simulations
indicate that the activated Zn atoms are the dominant active sites
via the formation of a Zn–OH bond with H2O. Especially,
the strong interactions of electrons in atomic orbitals at vacancy
pairs and the introduction of VZn are conducive to high
stability. The optimal sample maintains an average hydrogen production
rate of 6.59 mmol·g–1·h–1 (300 W Xe lamp) after nine cycles. Hence, this work deepens the
understanding of vacancy defects and provides an idea for the design
of a stable photocatalyst.
For developing highly sensitive, selective and stable gas sensing materials for the detection of volatile organic compounds, we report porous micro/nano-level structured Ag-LaFeO3 nanoparticles which have been successfully synthesized using a lotus leaf as a bio-template via a sol–gel process.
Silver-doped LaFeO molecularly imprinted polymers (SLMIPs) were synthesized by a sol-gel method combined with molecularly imprinted technology as precursors. The precursors were then used to prepare SLMIPs cage (SLM-cage) and SLMIPs core-shell (SLM-core-shell) structures by using a carbon sphere as the template and hydrothermal synthesis, respectively. The structures, morphologies, and surface areas of these materials were determined, as well as their gas-sensing properties and related mechanisms. The SLM-cage and SLM-core-shell samples exhibited good responses to methanol gas, with excellent selectivity. The response and optimum working temperature were 16.98 °C and 215 °C, 33.7 °C and 195 °C, respectively, with corresponding response and recovery times of 45 and 50 s (SLM-cage) and 42 and 57 s (SLM-core-shell) for 5 ppm methanol gas. Notably, the SLM-cage and SLM-core-shell samples exhibited lower responses (≤5 and ≤7, respectively) to other gases, including ethanol, ammonia, benzene, acetone, and toluene. Thus, these materials show potential as practical methanol detectors.
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