Segmented Ag-Au-Ag Heterojunction Nanorods: Pressure-Assisted Aqueous-Phase Synthesis and Engineered Femtosecond-to-Nanosecond Dynamics

A multifunctional interlayer activated by lithiophilic electrospun Ag nanowires/polyvinylpyrrolidone nanofibers for efficient lithium storage

A three-dimensional lithiophilic electrospun nanofiber framework with a Ag nanowires/polyvinylpyrrolidone (AgNWs/PVP) hybrid as a multifunctional interlayer has been designed to protect lithium metal anodes. The full cells with a LiFePO4 cathode and AgNWs/PVP interlayer have also realized excellent stable cyclability over 1000 cycles and high-rate capability.

Verifying the Charge-Transfer Mechanism in S-Scheme Heterojunctions Using Femtosecond Transient Absorption Spectroscopy

The S-scheme heterojunction is flourishing in photocatalysis because it concurrently realizes separated charge carriers and sufficient redox ability. Steady-state charge transfer has been confirmed by other methods. However, an essential part, the transfer dynamics in S-scheme heterojunctions, is still missing. To compensate, a series of cadmium sulfide/pyrene-alt-difluorinated benzothiadiazole heterojunctions were constructed and the photophysical processes were investigated with femtosecond transient absorption spectroscopy. Encouragingly, an interfacial charge-transfer signal was detected in the spectra of the heterojunction, which provides solid evidence for S-scheme charge transfer to complement the results from well-established methods. Furthermore, the lifetime for interfacial charge transfer was calculated to be ca. 78.6 ps. Moreover, the S-scheme heterojunction photocatalysts exhibit higher photocatalytic conversion of 1,2-diols and H₂ production rates than bare cadmium sulfide.

Electrical transport properties of TiO2/MAPbI3 and SnO2/MAPbI3 heterojunction interfaces under high pressure

The electrical transport properties of SnO₂(TiO₂)/MAPbI₃ (MA = CH₃NH₃ ⁺) heterojunction interfaces are investigated from ambient pressure to 20 GPa, and the transport properties are calculated by physical parameters such as trap energy density, binding energy, and charge transfer driving force and defect. Based on the partial density of states (PDOS) of the SnO₂/MAPbI₃ heterojunction interface MAI-termination and PbI₂-termination, greater charge transfer driving force and higher binding energy are observed, obviously showing the SnO₂-based heterojunction is more stable. The SnO₂/MAPbI₃ heterojunction interface possesses stronger electrical transport ability and is less prone to capture electrons compared with the TiO₂/MAPbI₃ heterojunction interface. The differential charge density spectrum shows that the density is lower in the trap energy level of SnO₂/MAPbI₃, whilst the effect of the charge transfer defect is weaker owing to the trap energy level only existing in SnO₂. The SnO₂/MAPbI₃ heterostructure interface is less prone to capture electrons. The greater electron concentration difference is attributed to oxygen vacancy (Vo₀) in the SnO-like environment, resulting in superior electron transport ability compared with the TiO-like environment.

Instantly Detecting Catalysts' Hot Spots Temperature In Situ during Photocatalysis by Operando Raman Spectroscopy

Precisely detecting the catalysts' hot spots temperature in situ instantly during photocatalysis is a great challenge but extremely important for chemical reactions. However, no efficient method has been developed to instantly detect the hot spots temperature in situ during photocatalysis. Herein, we designed a simple and convenient method to measure the instant hot spots temperature in situ on the nanostructure surface during photocatalysis by operando Raman spectroscopy using 4-methoxyphenyl isocyanide (MI) as the probe molecule. The ν_N≡C frequency of MI varied linearly with temperature, which is caused by the orientation change of the MI induced by temperature, leading to the change in the frequency of the ν_N≡C bond that directly interacts with the nanostructure surface. Using in situ surface-enhanced Raman spectroscopy (SERS), the surface temperature of the catalysts illuminating for each time can be measured instantly. Interestingly, the catalytic activity of the hydrogen evolution reaction (HER) for the Au-Ag/Ag₂S heterojunction nanorods (HJNRs) are higher than that for the Ag-Au-Ag HJNRs, although they have a lower surface temperature during photocatalysis; therefore, hot carriers and electronic structure contributed more to the catalytic activity of the Au-Ag/Ag₂S HJNRs than that of the Ag-Au-Ag HJNRs. Such an instant hot spots temperature detecting method of catalysts can greatly facilitate the analysis of the mechanism of catalytic processes.

Controlling alloy to core-shell structure transformation of Au-Pd icosahedral nanoparticles

The structure transformation between Au-Pd alloy and core-shell icosahedral nanoparticles was achieved by a one-step aqueous-phase strategy. This strategy provided a way to tune the structure and atomic distribution of Au-Pd icosahedral nanoparticles. It could modulate the electronic structure of Pd, achieving promoted electrocatalytic ability toward the hydrogen evolution reaction.