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Design of metal-semiconductor interfaces and heterostructures is of strong interest for various catalytic applications including photocatalysis. In this work, a series of hollow Au nanosphere (HGN)-Cu2O core-shell nanostructures with varying core surface rugosities are synthesized and investigated for possible photocatalytic applications. HGN surface rugosity is tuned by pH modification during galvanic exchange, and carboxyl groups are utilized as coordination sites to deposit uniform Cu2O shells onto the gold surfaces. Final core-shell structures are verified by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), and X-ray diffraction (XRD). Information regarding chemical state and electronic band structure is acquired by X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). Ultrafast transient absorption (TA) reveals that charge separation in bumpy HGN (bHGN)-Cu2O may effectively provide longer-lived photoexcited carriers, offering great potential for utilization in advanced photocatalytic processes.

This study presents the synthesis and characterization of Au nanoparticle-decorated BiFeO3 (Au-BiFeO3) nanocrystals fabricated by a hydrothermal technique. The key focus is the augmented photocatalytic properties of these nanocrystals for the effective photodegradation of methylene blue (MB), a common industrial dye. The magnetic properties of the Au-BiFeO3 merely differ from those of the BiFeO3. The decoration of Au nanoparticles onto the BiFeO3 introduces heterojunction structures that lead to effective charge-carrier separation under illumination. Time-resolved photoluminescence spectroscopy confirms the enhanced charge separation and reduced recombination rate in Au-BiFeO3 nanocrystals. Through meticulous optimization, the photocatalytic performance of these nanocomposites was evaluated under various Au loadings, revealing that 1.0 wt % Au-BiFeO3 exhibits the most superior activity, achieving an impressive 98% degradation efficiency of MB under a 500 W xenon lamp within 120 min. The study also demonstrates the structural integrity and stability of the photocatalyst, with it retaining about 80% of its original activity after four cycles of the 120 min photodegradation process. These findings suggest that the Au-BiFeO3 nanocrystals are promising, efficient, and sustainable photocatalysts for environmental purification and offer insights into designing advanced materials for solar energy utilization. [ABSTRACT FROM AUTHOR]

Using in situ ultrafast laser spectroscopic techniques to monitor the charge dynamics of semiconductor photocatalysts under operating conditions is essential for digging out the veritable interactions between charge carriers and the reactive species. This real-time observation is desirable for optimizing individual components and their integration in advanced photoelectrochemical (PEC) and photocatalytic systems, which can achieve the “Holy Grail” of solar energy harvesting and solar fuel generation. This Review summarizes the recent developments of employing transient absorption spectroscopy for in situ measurements of charge dynamics on semiconductor nanostructures. The implications in the PEC and photocatalytic reactions toward hydrogen production and carbon dioxide reduction will be discussed, along with future outlooks and perspectives.

The COVID‐19 pandemic has underscored the paramount importance of maintaining clean and safe environments. Strengthening environmental purification measures is pivotal for better preparedness and resilience against future health crises. Photocatalytic fibers, due to their versatility and adaptability to various application scenarios, play a pivotal role in the field of environmental purification. In this perspective, light is shed on the pivotal advancements in employing photocatalytic fibers to tackle environmental issues encompassing dye degradation, antibiotics decomposition, heavy metal removal, indoor air purification, and microbial disinfection. These applications hold significant promise in promoting cleaner and healthier environments while aligning with sustainability objectives. However, the implementation of photocatalytic fibers in practical scenarios is not without its challenges. Issues, such as near infrared responsiveness, all‐day active capacity, reusability, and scalability, must be addressed to ensure their reliability and long‐term effectiveness. Potential solutions for surmounting these challenges are also delved, aiming to provide a comprehensive overview for researchers and stakeholders. Exploring new avenues and innovative approaches may pave the way for the widespread deployment of photocatalytic fibers in environmental purification, especially in the post‐pandemic era where the need for clean and safe environments is more evident than ever. [ABSTRACT FROM AUTHOR]

Near infrared energy remains untapped toward the maneuvering of entire solar spectrum harvesting for fulfilling the nuts and bolts of solar hydrogen production. We report the use of Au@Cu7S4 yolk@shell nanocrystals as dual-plasmonic photocatalysts to achieve remarkable hydrogen production under visible and near infrared illumination. Ultrafast spectroscopic data reveal the prevalence of long-lived charge separation states for Au@Cu7S4 under both visible and near infrared excitation. Combined with the advantageous features of yolk@shell nanostructures, Au@Cu7S4 achieves a peak quantum yield of 9.4% at 500 nm and a record-breaking quantum yield of 7.3% at 2200 nm for hydrogen production in the absence of additional co-catalysts. The design of a sustainable visible- and near infrared-responsive photocatalytic system is expected to inspire further widespread applications in solar fuel generation. In this work, the feasibility of exploiting the localized surface plasmon resonance property of self-doped, nonstoichiometric semiconductor nanocrystals for the realization of wide-spectrum-driven photocatalysis is highlighted. Near infrared energy remains untapped toward the maneuvering of entire solar spectrum harvesting for fulfilling nuts and bolts of solar hydrogen production. Here, the authors report the use of Au@Cu7S4 yolk@shell nanocrystals for hydrogen production from untapped near infrared energy. [ABSTRACT FROM AUTHOR]