Detecting and Quantifying Wavelength-Dependent Electrons Transfer in Heterostructure Catalyst via In Situ Irradiation XPS

Photo-Assisted Rechargeable Metal Batteries: Principles, Progress, and Perspectives

The utilization of diverse energy storage devices is imperative in the contemporary society. Taking advantage of solar power, a significant environmentally friendly and sustainable energy resource, holds great appeal for future storage of energy because it can solve the dilemma of fossil energy depletion and the resulting environmental problems once and for all. Recently, photo-assisted energy storage devices, especially photo-assisted rechargeable metal batteries, are rapidly developed owing to the ability to efficiently convert and store solar energy and the simple configuration, as well as the fact that conventional Li/Zn-ion batteries are widely commercialized. Considering many puzzles arising from the rapid development of photo-assisted rechargeable metal batteries, this review commences by introducing the fundamental concepts of batteries and photo-electrochemistry, followed by an exploration of the current advancements in photo-assisted rechargeable metal batteries. Specifically, it delves into the elucidation of device components, operating principles, types, and practical applications. Furthermore, this paper categorizes, specifies, and summarizes several detailed examples of photo-assisted energy storage devices. Lastly, it addresses the challenges and bottlenecks faced by these energy storage systems while providing future perspectives to facilitate their transition from laboratory research to industrial implementation.

Rational Design of Three Dimensional Hollow Heterojunctions for Efficient Photocatalytic Hydrogen Evolution Applications

The efficiency of photocatalytic hydrogen evolution is currently limited by poor light adsorption, rapid recombination of photogenerated carriers, and ineffective surface reaction rate. Although heterojunctions with innovative morphologies and structures can strengthen built-in electric fields and maximize the separation of photogenerated charges. However, how to rational design of novel multidimensional structures to simultaneously improve the above three bottleneck problems is still a research imperative. Herein, a unique Cu2O─S@graphene oxide (GO)@Zn0.67Cd0.33S Three dimensional (3D) hollow heterostructure is designed and synthesized, which greatly extends the carrier lifetime and effectively promotes the separation of photogenerated charges. The H2 production rate reached 48.5 mmol g-1 h-1 under visible light after loading Ni2+ on the heterojunction surface, which is 97 times higher than that of pure Zn0.67Cd0.33S nanospheres. Furthermore, the H2 production rate can reach 77.3 mmol g-1 h-1 without cooling, verifying the effectiveness of the photothermal effect. Meanwhile, in situ characterization and density flooding theory calculations reveal the efficient charge transfer at the p-n 3D hollow heterojunction interface. This study not only reveals the detailed mechanism of photocatalytic hydrogen evolution in depth but also rationalizes the construction of superior 3D hollow heterojunctions, thus providing a universal strategy for the materials-by-design of high-performance heterojunctions.

Sulfur defect induced Cd0.3Zn0.7S in-situ anchoring on metal organic framework for enhanced photothermal catalytic CO2 reduction to prepare proportionally adjustable syngas

The rapid recombination of interfacial charges is considered to be the main obstacle limiting the photocatalytic CO2 reduction. Thus, it is a challenge to research an accurate and stable charge transfer control strategy. MIL-53 (Al)-S/Cd0.3Zn0.7S (MAS/CZS-0.3) photocatalysts with chemically bonded interfaces were constructed by in-situ electrostatic assembly of sulfur defect Cd0.3Zn0.7S (CZS-0.3) on the surface of MIL-53 (Al) (MAW), which enhanced interfacial coupling and accelerated electron transfer efficiency. An adjustable proportion of syngas (H2/CO) was prepared by photothermal catalytic CO2 reduction at micro-interface. and the optimal yield of CO (66.10 μmol∙g-1∙h-1) and H2 (71.0 μmol∙g-1∙h-1) was realized by the MAS/CZS-0.3 photocatalyst. The improved activity was due to the photogenerated electrons migrated from CZS-0.3 to the adsorption active sites of MAS, which strengthened the adsorption and activation of CO2 on MAS. The photothermal catalytic CO2 reduction to CO follows the pathway of CO2→*COOH → CO and CO2→*HCO3-→CO. This work provided a reference for the research, characterization, and application of in-situ anchoring of metal organic frameworks in photothermal catalytic CO2 reduction, and provided a green path for the supply of Syngas in industry.

Electrospinning Photocatalysis Meet In Situ Irradiated XPS: Recent Mechanisms Advances and Challenges

Producing solar fuels over photocatalysts under light irradiation is a considerable way to alleviate energy crises and environmental pollution. To develop the yields of solar fuels, photocatalysts with broad light absorption, fast charge carrier migration, and abundant reaction sites need to be designed. Electrospun 1D nanofibers with large specific areas and high porosity have been widely used in the efficient production of solar fuels. Nevertheless, it is challenging to do in-depth mechanism research on electrospun nanofiber-based photocatalysts since there are multiple charge transfer routes and various reaction sites in these systems. Here, the basic principles of electrospinning and photocatalysis are systemically discussed. Then, the different roles of electrospun nanofibers played in recent research to boost photocatalytic efficiency are highlighted. It is noteworthy that the working principles and main advantages of in situ irradiated photoelectron spectroscopy (ISI-XPS), a new technique to investigate migration routes of charge carriers and identify active sites in electrospun nanofibers based photocatalysts, are summarized for the first time. At last, a brief summary on the future orientation of photocatalysts based on electrospun nanofibers as well as the perspectives on the development of the ISI-XPS technique are also provided.

Two-Dimensional Atomically Thin Titanium Nitride via Topochemical Conversion

Titanium nitride as a typical transition metal nitride (TMN) has attracted increasing interest for its fascinating characteristics and widespread applications. However, the synthesis of two-dimensional (2D) atomically thin titanium nitride is still challenging which hinders its further research in electronic and optoelectronic fields. Here, 2D titanium nitride with a large area was prepared via in situ topochemical conversion of the titanate monolayer. The titanium nitride reveals a thickness-dependent metallic-to-semiconducting transition, where the atomically thin titanium nitride with a thickness of ∼1 nm exhibits an n-type semiconducting behavior and a highly sensitive photoresponse and displays photoswitchable resistance by repeated light irradiation. First-principles calculations confirm that the chemisorbed oxygen on the surface of the titanium nitride nanosheet depletes its electrons, while the light irradiation induced desorption of oxygen leads to increased electron doping and hence the conductance of titanium nitride. These results may allow the scalable synthesis of ultrathin TMNs and facilitate their fundamental physics research and next-generation optoelectronic applications.

Reversible Stacking of 2D ZnIn2 S4 Atomic Layers for Enhanced Photocatalytic Hydrogen Evolution

It is technically challenging to reversibly tune the layer number of 2D materials in the solution. Herein, a facile concentration modulation strategy is demonstrated to reversibly tailor the aggregation state of 2D ZnIn2 S4 (ZIS) atomic layers, and they are implemented for effective photocatalytic hydrogen (H2 ) evolution. By adjusting the colloidal concentration of ZIS (ZIS-X, X = 0.09, 0.25, or 3.0 mg mL-1 ), ZIS atomic layers exhibit the significant aggregation of (006) facet stacking in the solution, leading to the bandgap shift from 3.21 to 2.66 eV. The colloidal stacked layers are further assembled into hollow microsphere after freeze-drying the solution into solid powders, which can be redispersed into colloidal solution with reversibility. The photocatalytic hydrogen evolution of ZIS-X colloids is evaluated, and the slightly aggregated ZIS-0.25 displays the enhanced photocatalytic H2 evolution rates (1.11 µmol m-2 h-1 ). The charge-transfer/recombination dynamics are characterized by time-resolved photoluminescence (TRPL) spectroscopy, and ZIS-0.25 displays the longest lifetime (5.55 µs), consistent with the best photocatalytic performance. This work provides a facile, consecutive, and reversible strategy for regulating the photo-electrochemical properties of 2D ZIS, which is beneficial for efficient solar energy conversion.

In Situ Formation ZnIn2 S4 /Mo2 TiC2 Schottky Junction for Accelerating Photocatalytic Hydrogen Evolution Kinetics: Manipulation of Local Coordination and Electronic Structure

Regulating electronic structures of the active site by manipulating the local coordination is one of the advantageous means to improve photocatalytic hydrogen evolution (PHE) kinetics. Herein, the ZnIn₂ S₄ /Mo₂ TiC₂ Schottky junctions are designed to be constructed through the interfacial local coordination of In³⁺ with the electronegative O terminal group on Mo₂ TiC₂ based on the different work functions. Kelvin probe force microscopy and charge density difference reveal that an electronic unidirectional transport channel across the Schottky interface from ZnIn₂ S₄ to Mo₂ TiC₂ is established by the formed local nucleophilic/electrophilic region. The increased local electron density of Mo₂ TiC₂ inhibits the backflow of electrons, boosts the charge transfer and separation, and optimizes the hydrogen adsorption energy. Therefore, the ZnIn₂ S₄ /Mo₂ TiC₂ photocatalyst exhibits a superior PHE rate of 3.12 mmol g^-1 h^-1 under visible light, reaching 3.03 times that of the pristine ZnIn₂ S₄ . This work provides some insights and inspiration for preparing MXene-based Schottky catalysts to accelerate PHE kinetics.

Revealing the Selective Bifunctional Electrocatalytic Sites via In Situ Irradiated X-Ray Photoelectron Spectroscopy for Lithium-Sulfur Battery

The electrocatalysts are widely applied in lithium-sulfur (Li-S) batteries to selectively accelerate the redox kinetics behavior of Li2 S, in which bifunctional active sites are established, thereby improving the electrochemical performance of the battery. Considering that the Li-S battery is a complex closed "black box" system, the internal redox reaction routes and active sites cannot be directly observed and monitored especially due to the distribution of potential active-site structures and their dynamic reconstruction. Empirical evidence demonstrates that traditional electrochemical test methods and theoretical calculations only probe the net result of multi-factors on an average and whole scale. Herein, based on the amorphous TiO2- x @Ni selective bifunctional model catalyst, these limitations are overcome by developing a system that couples the light field and in situ irradiated X-ray photoelectron spectroscopy to synergistically convert the "black box" battery into a "see-through" battery for direct observation of the charge transportation, thus revealing that amorphous TiO2- x and Ni nanoparticle as the oxidation and reduction sites selectively promote the decomposition and nucleation of Li2 S, respectively. This work provides a universal method to achieve a deeper mechanistic understanding of bidirectional sulfur electrochemistry.

Revealing Photocatalytic Performance of ZnxCd1-xS Nanoparticles Depending on the Irradiation Wavelength

Photocatalysts are useful for various applications, including the conservation and storage of energy, wastewater treatment, air purification, semiconductors, and production of high-value-added products. Herein, Zn_xCd_1-xS nanoparticle (NP) photocatalysts with different concentrations of Zn²⁺ ions (x = 0.0, 0.3, 0.5, or 0.7) were successfully synthesized. The photocatalytic activities of Zn_xCd_1-xS NPs varied with the irradiation wavelength. X-ray diffraction, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, and ultraviolet-visible spectroscopy were used to characterize the surface morphology and electronic properties of the Zn_xCd_1-xS NPs. In addition, in situ X-ray photoelectron spectroscopy was performed to investigate the effect of the concentration of Zn²⁺ ions on the irradiation wavelength for photocatalytic activity. Furthermore, wavelength-dependent photocatalytic degradation (PCD) activity of the Zn_xCd_1-xS NPs was investigated using biomass-derived 2,5-hydroxymethylfurfural (HMF). We observed that the selective oxidation of HMF using Zn_xCd_1-xS NPs resulted in the formation of 2,5-furandicarboxylic acid via 5-hydroxymethyl-2-furancarboxylic acid or 2,5-diformylfuran. The selective oxidation of HMF was dependent on the irradiation wavelength for PCD. Moreover, the irradiation wavelength for the PCD depended on the concentration of Zn²⁺ ions in the Zn_xCd_1-xS NPs.