Ordered colloidal clusters constructed by nanocrystals with valence for efficient CO2 photoreduction

Regioselective super-assembly of Prussian blue analogue

The construction of high-asymmetrical structures demonstrates significant potential in improving the functionality and distinctness of nanomaterials, but remains a considerable challenge. Herein, we develop a one-pot method to fabricate regioselective super-assembly of Prussian blue analogue (PBA) -- a PBA anisotropic structure (PBA-AS) decorated with epitaxial modules--using a step-by-step epitaxial growth on a rapidly self-assembled cubic substrate guided by thiocyanuric acid (TCA) molecules. The epitaxial growth units manifest as diverse geometric shapes, which are predominantly concentrated on the {100}, {111}, or {100}+{111} crystal plane of the cubic substrate. The crystal plane and morphology of epitaxial module can be regulated by changing the TCA concentration and reaction temperature, enabling a high level of controllability over specific assembly sites and structures. To illustrate the advantage of the asymmetrical structure, phosphated PBA-AS demonstrates improved performance in the oxygen evolution reaction compared to simple phosphated PBA nanocube. This method offers valuable insights for designing asymmetrical nanomaterials with intricate architectures and versatile functionalities.

Asymmetric Atomic Dual-Sites for Photocatalytic CO2 Reduction

Atomically dispersed active sites in a photocatalyst offer unique advantages such as locally tuned electronic structures, quantum size effects, and maximum utilization of atomic species. Among these, asymmetric atomic dual-sites are of particular interest because their asymmetric charge distribution generates a local built-in electric potential to enhance charge separation and transfer. Moreover, the dual sites provide flexibility for tuning complex multielectron and multireaction pathways, such as CO2 reduction reactions. The coordination of dual sites opens new possibilities for engineering the structure-activity-selectivity relationship. This comprehensive overview discusses efficient and sustainable photocatalysis processes in photocatalytic CO2 reduction, focusing on strategic active-site design and future challenges. It serves as a timely reference for the design and development of photocatalytic conversion processes, specifically exploring the utilization of asymmetric atomic dual-sites for complex photocatalytic conversion pathways, here exemplified by the conversion of CO2 into valuable chemicals.

Prussian Blue Analogue Glasses for Photoinduced CO2 Conversion

Crystal-to-glass transformation is a powerful approach to modulating the chemical and physical properties of crystals. Here we demonstrate that the glass transformation of cobalt hexacyanoferrate crystals, one of the Prussian blue analogues, increased the concentration of open metal sites and altered the electronic state while maintaining coordination geometries and short-range ordering in the structure. The compositional and structural changes were characterized by X-ray absorption fine structure, energy dispersive X-ray spectroscopy, and X-ray total scattering. The changes contribute to the flat band potential of the glass becoming closer to the redox potential of CO2 reduction. The valence band energy of the glass also shifts, resulting in lower band gap energy. Both the increased open metal sites and the optimal electronic structure upon vitrification enhance photocatalytic activity toward CO2-to-CO conversions (9.9 μmol h-1 CO production) and selectivity (72.4%) in comparison with the crystalline counterpart (3.9 μmol h-1 and 42.8%).

Highly Crystalline Multivariate Prussian Blue Analogs via Equilibrium Chelation Strategy for Stable and Fast Charging Sodium-Ion Batteries

Prussian blue analogs (PBAs) have been widely recognized as superior cathode materials for sodium-ion batteries (SIBs) owing to numerous merits. However, originating from the rapid crystal growth, PBAs still suffer from considerable vacancy defects and interstitial water, making the preparation of long-cycle-life PBAs the greatest challenge for its practical application. Herein, a novel equilibrium chelation strategy is first proposed to synthesize a high crystallinity (94.7%) PBAs, which is realized by modulating the chelating potency of strong chelating agents via "acid effect" to achieve a moderate chelating effect, forcefully breaking through the bottleneck of poor cyclic stability for PBAs cathodes. Impressively, the as-prepared highly crystalline PBAs represent an unprecedented level of electrochemical performance including ultra-long lifespan (10000 cycles with 86.32% capacity maintenance at 6 A g-1), excellent rate capability (82.0 mAh g-1 at 6 A g-1). Meanwhile, by pairing with commercial hard carbon, the as-prepared PBAs-based SIBs exhibit high energy density (350 Wh kg-1) and excellent capacity retention (82.4% after 1500 cycles), highlighting its promising potential for large-scale energy storage applications.

Hierarchically Ordered Pore Engineering of Metal-Organic Framework-Based Materials for Electrocatalysis

Ordered pore engineering that embeds uniform pores with periodic alignment in electrocatalysts opens up a new avenue for achieving further performance promotion. Hierarchically ordered porous metal-organic frameworks (HOP-MOFs) possessing multilevel pores with ordered distribution are the promising precursors for the exploration of ordered porous electrocatalysts, while the scalable acquisition of HOP-MOFs with editable components and adjustable pore size regimes is critical. This review presents recent progress on hierarchically ordered pore engineering of MOF-based materials for enhanced electrocatalysis. The synthetic strategies of HOP-MOFs with different pore size regimes, including the self-assembly guided by reticular chemistry, surfactant, nanoemulsion, and nanocasting, are first introduced. Then the applications of HOP-MOFs as the precursors for exploring hierarchically ordered porous electrocatalysts are summarized, selecting representatives to highlight the boosted performance. Especially, the intensification of molecule and ion transport integrated with optimized electron transfer and site exposure over the hierarchically ordered porous derivatives are emphasized to clarify the directional transfer and integration effect endowed by ordered pore engineering. Finally, the remaining scientific challenges and an outlook of this field are proposed. It is hoped that this review will guide the hierarchically ordered pore engineering of nanocatalysts for boosting the catalytic performance and promoting the practical applications.

Triple-Phase Photocatalytic H2O2 Production on a Janus Fiber Membrane with Asymmetric Hydrophobicity

Photocatalytic O2 reduction is an intriguing approach to producing H2O2, but its efficiency is often hindered by the limited solubility and mass transfer of O2 in the aqueous phase. Here, we design and fabricate a two-layered (2L) Janus fiber membrane photocatalyst with asymmetric hydrophobicity for efficient photocatalytic H2O2 production. The top layer of the membrane consists of superhydrophobic polytetrafluoroethylene (PTFE) fibers with a dispersed modified carbon nitride (mCN) photocatalyst. Amphiphilic Nafion (Naf) ionomer is sprayed onto this layer to modulate the microenvironment and achieve moderate hydrophobicity. In contrast, the bottom layer consists of bare PTFE fibers with high hydrophobicity. The elaborate structural configuration and asymmetric hydrophobicity feature of the optimized membrane photocatalyst (designated as 2L-mCN/F-Naf; F, PTFE) allow most mCN to be exposed with gas-liquid-solid triple-phase interfaces and enable rapid mass transfer of gaseous O2 within the hierarchical membrane, thus increasing the local O2 concentration near the mCN photocatalyst. As a result, the optimized 2L-mCN/F-Naf membrane photocatalyst shows remarkable photocatalytic H2O2 production activity, achieving a rate of 5.38 mmol g-1 h-1 under visible light irradiation.

Hydrogel Magnetomechanical Actuator Nanoparticles for Wireless Remote Control of Mechanosignaling In Vivo

As a new enabling nanotechnology tool for wireless, target-specific, and long-distance stimulation of mechanoreceptors in vivo, here we present a hydrogel magnetomechanical actuator (h-MMA) nanoparticle. To allow both deep-tissue penetration of input signals and efficient force generation, h-MMA integrates a two-step transduction mechanism that converts magnetic anisotropic energy to thermal energy within its magnetic core (i.e., Zn0.4Fe2.6O4 nanoparticle cluster) and then to mechanical energy to induce the surrounding polymer (i.e., pNiPMAm) shell contraction, finally delivering forces to activate targeted mechanoreceptors. We show that h-MMAs enable on-demand modulation of Notch signaling in both fluorescence reporter cell lines and a xenograft mouse model, demonstrating its utility as a powerful in vivo perturbation approach for mechanobiology interrogation in a minimally invasive and untethered manner.

Perspective and Prospects for Ordered Functional Materials

Many functional materials are approaching their performance limits due to inherent trade-offs between essential physical properties. Such trade-offs can be overcome by engineering a material that has an ordered arrangement of structural units, including constituent components/phases, grains, and domains. By rationally manipulating the ordering with abundant structural units at multiple length scales, the structural ordering opens up unprecedented opportunities to create transformative functional materials, as amplified properties or disruptive functionalities can be realized. In this perspective article, a brief overview of recent advances in the emerging ordered functional materials across catalytic, thermoelectric, and magnetic materials regarding the fabrication, structure, and property is presented. Then the possibility of applying this structural ordering strategy to highly efficient neuromorphic computing devices and durable battery materials is discussed. Finally, remaining scientific challenges are highlighted, and the prospects for ordered functional materials are made. This perspective aims to draw the attention of the scientific community to the emerging ordered functional materials and trigger intense studies on this topic.

Self-Assembled Tetratic Crystals by Orthogonal Colloidal Force

Bonding simple building blocks to create crystalline materials with design has been sophisticated in the molecular world, but this is still very challenging for anisotropic nanoparticles or colloids, because the particle arrangements, including position and orientation, cannot be manipulated as expected. Here biconcave polystyrene (PS) discs to present a shape self-recognition route are used, which can control both the position and orientation of particles during self-assembly by directional colloidal forces. An unusual but very challenging two-dimensional (2D) open superstructure-tetratic crystal (TC)-is achieved. The optical properties of the 2D TCs are studied by the finite difference time domain method, showing that the PS/Ag binary TC can be used to modulate the polarization state of the incident light, for example, converting the linearly polarized light into left-handed or right-handed circularly polarized light. This work paves an important way for self-assembling many unprecedented crystalline materials.

Design and Self-Assembly of Polyhedron Particles to Construct Iridescent Structural Colors

Polyhedron particles exhibit unique physical properties in constructing novel materials. Here, the polystyrene (PS) polyhedron particles were fabricated via dispersion polymerization, and their morphologies can be controlled by tuning the divinylbenzene (DVB) content and polarity of the reaction medium. The possible formation mechanism is the asymmetric distribution of cross-linked networks during the phase separation process. In addition, the large-scale iridescent structural colors based on polyhedrons were obtained and further explored their applications in smart displays. This presented method guides the fabrication of anisotropic particles and their further assembly to construct novel materials.

Bionic Optical Leaf for Photoreduction of CO2 from Noble Metal Atom Mediated Graphene Nanobubble Arrays

The reduction of CO₂ to useful chemicals by solar irradiation has been of great interest in recent years to tackle the greenhouse effect. Compared with inorganic metal oxide particles, carbonaceous materials, such as graphene, are excellent in light absorption; however, they lack in activity and selectivity because of the challenge to manipulate the band gap and optimize the electron-hole separation, which drives the photoreduction process. In this work, inspired by the delicate natural plant leaf structure, we fabricated orderly stacked graphene nanobubble arrays with nitrogen dopant for the coordination of noble metal atoms to mimic the natural photoreduction process in plant leaves. This graphene metamaterial not only mimics the optical structure of leaf cells, which scatter and absorb light efficiently, but also drives the CO₂ reduction via nitrogen coordinated metal atoms as the chlorophyll does in plants. Our characterizations show that the band gap of nitrogen-doped graphene could be precisely tailored via substitution with different noble metal atoms on the doped site. The noble atoms coordinated on the doped site of graphene metamaterial not only enlarge the light absorption volume but also maximize the utilization of noble metals. The bionic optical leaf metamaterial coordinated with Au atoms exhibits high CO productivity up to 11.14 mmol g_cat^-1 h^-1 and selectivity to 95%, standing as one of the best catalysts among the carbonaceous and metal-based catalysts reported to date. This catalyst also maintained a high performance at low temperatures, manifesting potential applications of this bionic catalyst at polar regions to reduce greenhouse gases.

Topotactic Epitaxy Self-Assembly of Potassium Manganese Hexacyanoferrate Superstructures for Highly Reversible Sodium-Ion Batteries

The cycle stability and voltage retention of a Na₂Mn[Fe(CN)₆] (NMF) cathode for sodium-ion batteries (SIBs) has been impeded by the huge distortion from NaMn^II[Fe^III(CN)₆] to Mn^III[Fe^III(CN)₆] caused by the Jahn-Teller (JT) effect of Mn³⁺. Herein, we propose a topotactic epitaxy process to generate K₂Mn[Fe(CN)₆] (KMF) submicron octahedra and assemble them into octahedral superstructures (OSs) by tuning the kinetics of topotactic transformation. As the SIB cathode, the self-assembly behavior of KMF improves the structural stability and decreases the contact area with the electrolyte, thereby inhibiting the transition metal in the KMF cathode from dissolving in the electrolyte. More importantly, the KMF partly transforms into NMF with Na⁺ de/intercalation, and the existing KMF acts as a stabilizer to disrupt the long-range JT order of NMF, thereby suppressing the overall JT distortion. As a result, the electrochemical performances of KMF cathodes outperform NMF with a highly reversible phase transition and outstanding cycling performance, and 80% capacity retention after 1500/1300 cycles at 0.1/0.5 A g^-1. This work not only promotes creative synthetic methodologies but also promotes to explore the relationship between Jahn-Teller structural deformation and cycle stability.

Phase Segregation via Etching-Induced Cation Migration in CoSx-ZnS Nanoarchitectures for Solar Hydrogen Evolution

Low charge carrier mobility limits the development of highly efficient semiconductor-based photocatalysis. Heterointerface engineering is a promising approach to spatially separate the photoexcited charge carriers and thus enhance photocatalytic activity....

Hierarchical, Highly Open Microtubes and Columnar Liquid Crystals Self-Assembled from Symmetrical and Asymmetrical Colloidal Rings

The use of simple building blocks to produce hierarchical and porous structured materials is highly desired. Rings are simple colloidal particles but unique for their internal cavities. Here we report the self-assembly (SA) of colloidal rings with tunable asymmetry mediated by a depletion force and demonstrate that a variety of porous colloidal superstructures from microtubes, flexible chains, (plastic) crystals to highly open liquid crystals (LCs) can be formed along the predesigned SA paths. In particular, the SA is staged in binary or ternary systems. Large rings first form complex ring-in-ring and ring-in-ring-in-ring assemblies by capturing smaller rings, which, as new building blocks, can further form multi-walled microtubes and open columnar LCs. Moreover, a plastic columnar LC with alternating intracolumnar stacking is found from asymmetrical rings. The SA with colloidal rings opens a new avenue to construct hierarchical and porous ordered metamaterials.

Versatile Synthesis of Hollow Metal Sulfides via Reverse Cation Exchange Reactions for Photocatalytic CO2 Reduction

Herein, we explore a general Cu_2-x S nanocube template-assisted and reverse cation exchange-mediated growth strategy for fabricating hollow multinary metal sulfide. Unlike the traditional cation exchange method controlled by the metal sulfide constant, the introduction of tri-n-butylphosphine (TBP) can reverse cation exchange to give a series of hollow metal sulfides. A variety of hollow multinary metal sulfide cubic nanostructures has been demonstrated while preserving anisotropic shapes to the as-synthesized templates, including binary compounds (CdS, ZnS, Ag₂ S, PbS, SnS), ternary compound (CuInS₂ , Zn_x Cd_1-x S), and quaternary compound (single-atom platinum anchored Zn_x Cd_1-x S; Zn_x Cd_1-x S-Pt₁ ). Experimental and density functional theory (DFT) calculations show that the hollow metal sulfide semiconductors obtained could significantly improve the separation and migration of photogenerated electron-hole pairs. Owing to the efficient charge transfer, the Zn_x Cd_1-x S-Pt₁ exhibited outstanding photocatalytic performance of CO₂ to CO, with the highest CO generation rate of 75.31 μmol h^-1 .

Well-defined Co9S8 cages enable the separation of photoexcited charges to promote visible-light CO2 reduction

Exploring affordable cocatalysts with high performance for boosting charge separation and CO₂ activation is an effective strategy to reinforce CO₂ photoreduction efficiency. Herein, well-defined Co₉S₈ cages are exploited as a nonprecious promoter for visible-light CO₂ reduction. The Co₉S₈ cages are prepared via a multistep strategy with ZIF-67 particles as the precursor and fully characterized by physicochemical techniques. The hollow Co₉S₈ cocatalyst with a high surface area and profuse catalytically active centers is discovered to accelerate separation and transfer of light-induced charges, and strengthen concentration and activation of CO₂ molecules. In a hybrid photosensitized system, these Co₉S₈ cages efficiently promote the deoxygenative reduction of CO₂ to generate CO, with a high yield rate of 35 μmol h^-1 (i.e., 35 mmol h^-1 g^-1). Besides, this cocatalyst is also of high stability for the CO₂ photoreduction reaction. Density functional theory (DFT) calculations reveal that the Ru(bpy)₃²⁺ photosensitizer is strongly absorbed on the Co₉S₈ (311) surface through forming four Co-C bonds, which can serve as the "bridges" to ensure quick electron transfer from the excited photosensitiser to the active Co₉S₈ cocatalyst, thus promoting the separation of photoexcited charges for ehannced CO₂ reduction performance.

Single PEDOT Catalyst Boosts CO2 Photoreduction Efficiency

Atmospheric pollution demands the development of solar-driven photocatalytic technologies for the conversion of CO₂ into a fuel; state-of-the-art cocatalyst systems demonstrate conversion efficiencies currently unattainable by a single catalyst. Here, we upend the status quo demonstrating that the nanofibrillar conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) is a record-breaking single catalyst for the photoreduction of CO₂ to CO. This high catalytic efficiency stems from a highly conductive nanofibrillar structure that significantly enhances surface area, CO₂ adsorption and light absorption. Moreover, the polymer's band gap is optimized via chemical doping/dedoping treatments using hydrochloric acid, ammonia hydroxide, and hydrazine. The hydrazine-treated PEDOT catalyst exhibits 100% CO yield under a stable regime (>10 h) with a maximum rate of CO evolution (3000 μmol g_cat ^-1 h^-1) that is 2 orders of magnitude higher than the top performing single catalyst and surpassed only by three other cocatalyst systems. Nanofibrillar PEDOT provides a new direction for designing the next generation of high-efficiency photoreduction catalysts.

General Route to Colloidal Nanocrystal Clusters with Precise Hierarchical Control via Star-like Nanoreactors

A colloidal nanocrystal cluster (CNC) is a hierarchical nanostructure formed by clustering several nanocrystals into one nano-ensemble, which may exhibit unique optical or catalytic properties different from individual nanocrystals owing to the mutual interactions among neighboring component nanocrystals. However, there is still no universal synthetic route that could be applicable to diverse material compositions with precisely controlled hierarchical structures (i.e., nanocrystal number density, component nanocrystal size, and overall diameter of the CNC) up to now. Herein, a general and novel synthetic strategy was reported for crafting a wide range of inorganic CNCs (i.e., noble metal, semiconductor, and metal oxide) via utilizing amphiphilic star-like poly(4-vinylpyridine)-block-polystyrene diblock copolymers as nanoreactors prepared by sequential atom transfer radical polymerization. The hierarchical structure of rationally designed CNCs could be readily tailored by varying the P4VP molecular weight of star-like nanoreactors and the parameter optimization during the CNC preparation process, which was inaccessible by conventional synthetic methods.

Converting Organic Wastewater into CO Using MOFs-Derived Co/In2O3 Double-Shell Photocatalyst

The photocatalytic conversion of organic wastewater into value-added chemicals is a promising strategy to solve the environmental issue and energy crisis. Herein, Co/In₂O₃ nanotubes with a double-shell structure, as a highly efficient photocatalyst, are synthesized by a one-step calcination method. The Co/In₂O₃ heterostructure shows an outstanding photocatalytic CO₂ reduction performance of 4902 μmol h^-1 g^-1. Notably, these Co/In₂O₃ photocatalysts also achieve CO₂ self-generation and in situ reduction conversion in acid organic wastewater (phenol solution), in which the high CO₂ (47.5 μmol h^-1 g^-1) and CO (0.9 μmol h^-1 g^-1) evolution rates are demonstrated under solar irradiation. Transient photovoltage (TPV) tests demonstrate that Co nanoparticles on Co/In₂O₃ double-shell heterostructure serve as the CO₂ reduction sites for the effective capture and stabilization of the photogenerated electrons.

Assembly of Colloidal Clusters Driven by the Polyhedral Shape of Metal-Organic Framework Particles

Control of the assembly of colloidal particles into discrete or higher-dimensional architectures is important for the design of myriad materials, including plasmonic sensing systems and photonic crystals. Here, we report a new approach that uses the polyhedral shape of metal–organic-framework (MOF) particles to direct the assembly of colloidal clusters. This approach is based on controlling the attachment of a single spherical polystyrene particle on each face of a polyhedral particle via colloidal fusion synthesis, so that the polyhedral shape defines the final coordination number, which is equal to the number of faces, and geometry of the assembled colloidal cluster. As a proof of concept, we assembled six-coordinated (6-c) octahedral and 8-c cubic clusters using cubic ZIF-8 and octahedral UiO-66 core particles. Moreover, we extended this approach to synthesize a highly coordinated 12-c cuboctahedral cluster from a rhombic dodecahedral ZIF-8 particle. We anticipate that the synthesized colloidal clusters could be further evolved into spherical core–shell MOF@polystyrene particles under conditions that promote a higher fusion degree, thus expanding the methods available for the synthesis of MOF–polymer composites.

Elegant Construction of ZnIn2S4/BiVO4 Hierarchical Heterostructures as Direct Z-Scheme Photocatalysts for Efficient CO2 Photoreduction

The ZnIn₂S₄/BiVO₄ heterostructures were elegantly designed through assembling ZnIn₂S₄ nanosheets onto the surface of BiVO₄ decahedrons. This composite photocatalyst exhibits efficient photocatalytic conversion of CO₂ into CO with a detectable amount of CH₄ in the presence of water vapor. An electron spin-resonance spectroscopy (ESR) technique and density function theory (DFT) calculation affirm the direct Z-scheme structure in ZnIn₂S₄/BiVO₄. The larger surface photovoltage (SPV) change and the longer liquid photoluminescence (PL) lifetime of the heterostructure, compared to the individual ZnIn₂S₄ and BiVO₄ components, demonstrate that the Z-scheme structure can effectively promote the recombination of the photogenerated holes in the valence band (VB) of the ZnIn₂S₄ nanosheet with the electrons in the conduction band (CB) of the decahedral BiVO₄ and lead to the abundant electrons surviving in the CB of ZnIn₂S₄ and holes in the VB of BiVO₄, thus enhancing photocatalytic CO₂ reduction performance. This study may make a potential contribution to the rational construction and deep understanding of the underlying mechanism of direct Z-schemes for advanced photocatalytic activity.

High selective photocatalytic CO2 conversion into liquid solar fuel over a cobalt porphyrin-based metal-organic framework

In the present study, porphyrin-based metal-organic framework (Co/PMOF) was synthesized and characterized by different spectra analyses. The photoluminescence properties of porphyrin and Co/PMOF revealed that the photoluminescence of Co/PMOF was quenched compared to the porphyrin, indicating that the lifetime of photo-generated charge carriers in Co/PMOF is longer than porphyrin. The prepared Co/PMOF was applied as an efficient photocatalyst for CO₂ photoconversion to formate in the presence of triethanolamine (TEOA) as a sacrificial agent under visible-light irradiation. The photoreaction results showed that 23.21 µmol HCOO^- was produced over Co/PMOF during the 6 h photocatalytic reaction under visible illumination, showing much better activity than the porphyrin, 4.56 µmol HCOO^-. No other products were detected, suggesting that this reaction over Co/PMOF has high selectivity. Co/PMOF reusability and stability were examined through recycling tests and there were no remarkable losses of photoactivity even after three cycles of photoreaction. Moreover, FTIR measurement and UV-Vis spectra demonstrated no notable changes in Co/PMOF structure. As a result, superior photocatalytic behavior of Co/PMOF was implied for CO₂ photoreduction which highlights the great potential of assembly porphyrin and cobalt into MOFs for CO₂ photoreduction.

Tuning Crystallinity and Surface Hydrophobicity of a Cobalt Phosphide Cocatalyst to Boost CO2 Photoreduction Performance

Photocatalytic CO₂ conversion is a promising method to yield carbon fuels, but it remains challenging to regulate catalytic materials for enhanced reaction efficiency and tunable product selectivity. This study concerns the development of a facile and efficient thermal post-treatment method to improve the crystallinity and surface hydrophobicity of a cobalt phosphide (CoP) cocatalyst, which promotes the separation and transfer of photoexcited charge carriers, reinforces CO₂ chemisorption, and weakens the H₂ O affinity. Compared with pristine CoP, the optimal CoP-600 cocatalyst displays a 3.5-fold enhancement in activity and a 2.3-fold increase in selectivity for the reduction of CO₂ to CO with a high rate of 68.1 μmol h^-1 .

Branched In2O3 Mesocrystal of Ordered Architecture Derived from the Oriented Alignment of a Metal-Organic Framework for Accelerated Hydrogen Evolution over In2O3-ZnIn2S4

It is fascinating yet challenging to assemble anisotropic nanowires into ordered architectures of high complexity and intriguing functions. We exploited a facile strategy involving oriented etching of a metal-organic fragment (MOF) to advance the rational design of highly ordered nanostructures. As a proof of concept, a microscale MIL-68(In) single crystal was etched with a K₃[Co(CN)₆] solution to give a microtube composed of aligned MIL-68(In) nanorods. Annealing such a MIL-68(In) microtube readily created an unprecedented branched In₂O₃ mesocrystal by assembly of In₂O₃ nanorods aligned in order. The derived ordered-In₂O₃-ZnIn₂S₄ is more efficient in catalyzing visible-light-driven H₂ evolution (8753 μmol h^-1 g^-1) outperforming the disordered-In₂O₃-ZnIn₂S₄ counterpart (2700 μmol h^-1 g^-1) as well as many other state-of-the-art ZnIn₂S₄-based photocatalysts. The ordered architecture significantly boosts the short-range electron transfer in an In₂O₃-ZnIn₂S₄ heterojunction but has a negligible impact on the long-range electron transfer among In₂O₃ mesocrystals. The density functional theory (DFT) calculation reveals that the oriented etching is achieved by the selective binding of the [Co(CN)₆]^3- etchant on the (110) plane of MIL-68(In), which can drag the In atoms out of the framework in order. Our findings could broaden the technical sense toward advanced photocatalyst design and impose scientific impacts on unveiling how ordered photosystems operate.

Fabrication of CdS Frame-in-Cage Particles for Efficient Photocatalytic Hydrogen Generation under Visible-Light Irradiation

The design of advanced structures for semiconductor photocatalysts is an effective approach to enhance their performance toward solar-to-chemical energy conversion. Hollow and frame-like structures show advantageous features for photocatalytic reactions with enlarged surface area, shortened charge-transfer distance, promoted light-absorption ability, and enhanced mass-transfer capability. Here, a facile two-step sulfidation strategy is developed to fabricate unique CdS frame-in-cage particles for photocatalytic hydrogen generation. Cd-based Prussian blue analog (Cd-PBA) cubes are first converted to Cd-PBA cube-in-CdS cage particles, which are further transformed to CdS frame-in-cage particles. Benefiting from the novel frame-in-cage structure, the obtained CdS photocatalyst exhibits high activity under visible-light irradiation with the hydrogen generation rate of 13.6 mmol h^-1 g^-1 , which is much enhanced compared with those of the CdS cubes and cages.

Exquisite design of porous carbon microtubule-scaffolding hierarchical In2O3-ZnIn2S4 heterostructures toward efficient photocatalytic conversion of CO2 into CO

Porous carbon microtubule (PCMT)-scaffolding semiconductor heterostructures were exquisitely designed through the in situ growth of ZnIn₂S₄ (ZIS) ultrathin nanosheets onto In₂O₃ nanoparticle layers generated on the surface PCMT (abbreviated as PCMT@In₂O₃/ZIS) toward the efficient photocatalytic conversion of CO₂ into CO. The pronounced photocatalytic performance for CO₂ photoreduction into CO is attributed to a synergistic effect of the following factors: (1) the multistage hopping of the charge carriers among In₂O₃, ZIS, and PCMT greatly reduces the charge recombination in In₂O₃ and ZIS. (2) The mesoporous feature of the PCMT renders the large surface area and abundant active sites to accumulate the local concentration of CO₂ in the heterostructures. (3) The existence of a large amount of carbon defects in PCMT promotes the activity of the absorbed CO₂ molecules. (4) The tubular structures with two open ends of PCMT may favor the fast diffusion of the reactants and products, and the optical absorption can also be increased by multi-light scattering/reflection in the interior void. (5) The unique fabrication route leads to an intimate and tight contact among PCMT, In₂O₃, and ZIS, which is also favorable for the charge migration. This work makes a contribution to the development of a complex hollow photocatalysis system for artificial photosynthesis.