Solar-Driven Lignocellulose-to-H2 Conversion in Water using 2D-2D MoS2 /TiO2 Photocatalysts

As an alternative strategy for H₂ production under ambient conditions, solar-driven lignocellulose-to-H₂ conversion provides a very attractive approach to store and utilize solar energy sustainably. Exploiting efficient photocatalyst for photocatalytic lignocellulose-to-H₂ conversion is of huge significance and remains the key challenge for development of solar H₂ generation from lignocellulose. Herein, 2D-2D MoS₂ /TiO₂ photocatalysts with large 2D nanojunction were constructed for photocatalytic lignocellulose-to-H₂ conversion. In this smart structure, the 2D nanojunctions acted as efficient channel for charge transfer from TiO₂ to MoS₂ to improve charge separation efficiency and thus enhance photocatalytic lignocellulose-to-H₂ conversion activity. The 2 % MoS₂ /TiO₂ photocatalyst showed the highest photocatalytic lignocellulose-to-H₂ conversion performance with the maximal H₂ generation rate of 201 and 21.4 μmol h^-1  g^-1 in α-cellulose and poplar wood chip aqueous solution, respectively. The apparent quantum yield at 380 nm reached 1.45 % for 2 % 2D-2D TiO₂ /MoS₂ photocatalyst in α-cellulose aqueous solution. This work highlights the importance of optimizing the interface structures of photocatalyst for solar-driven lignocellulose-to-H₂ conversion.

Robust Molecular Dipole-Enabled Defect Passivation and Control of Energy-Level Alignment for High-Efficiency Perovskite Solar Cells

The ability to passivate defects and modulate the interface energy-level alignment (IEA) is key to boost the performance of perovskite solar cells (PSCs). Herein, we report a robust route that simultaneously allows defect passivation and reduced energy difference between perovskite and hole transport layer (HTL) via the judicious placement of polar chlorine-terminated silane molecules at the interface. Density functional theory (DFT) points to effective passivation of the halide vacancies on perovskite surface by the silane chlorine atoms. An integrated experimental and DFT study demonstrates that the dipole layer formed by the silane molecules decreases the perovskite work function, imparting an Ohmic character to the perovskite/HTL contact. The corresponding PSCs manifest a nearly 20 % increase in power conversion efficiency over pristine devices and a markedly enhanced device stability. As such, the use of polar molecules to passivate defects and tailor the IEA in PSCs presents a promising platform to advance the performance of PSCs.

Direct Electrochemical Protonation of Metal Oxide Particles

Metal oxides with surface protonation exhibit versatile physical and chemical properties suitable for use in many fields. Here, we develop an electrochemical route to directly protonize the physically assembled oxide particles, such as TiO₂, Nb₂O₅, and WO₃, in a Na₂SO₄ neutral electrolyte, which is a result of electrochemically induced oxygen vacancies reacting with water molecules. With no need of electric connection among particles or between particles and conductive substrate, the electrochemical protonation follows a bottom-up particle-by-particle surface protonation mechanism due to the fact that the protonation inducing high surface conductivity creates an efficient electron transfer pathway among particles. Our results show that electrochemical protonation of particles provides a chance to finely functionalize the surface of a single particle by only adjusting electrode potentials. Such a facile, cost-efficient, and green route is easy to run for a large-scale production and unlocks the potential of semiconductor oxides for various applications.

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.

Efficient Access to 3D Mesoscopic Prisms in Polymeric Soft Materials

The preparation of 3D functional isolated mesoscopic assemblies remains a challenge in the self-assembly of polymers. Here, well-defined 3D hexagonal and hexagram prisms with uniform dimensions are acquired by the crystallization of the inclusion complex composed of a crystalline molecule tris-o-phenylenedioxycyclotriphosphazene (TPP) and a block copolymer. The crystalline TPP plays an important role in the self-assembling process. The faceted morphologies of the hexagonal and hexagram prisms are infrequent in the self-assembly field of soft materials. The formation of the prisms experiences a 3D growth mechanism. The epitaxial growth, accompanied by the heterogeneous nucleation in the edges, yields the growth of inclusion crystals. This study provides a path to construct well-defined polymeric soft materials with broad utility based on numerous supramolecular complexes.

Solid-state redox couple mediated water splitting

The solid-state redox couple is a vital charge transfer medium for electrochemical water splitting. In this Frontiers article, we summarize the versatile application of redox couples in promoting OER kinetics, in decoupling the HER and OER, and in combined electrochemical-thermochemical water splitting. These new ideas unlock vast potential for applying redox-couple-mediated water splitting to the storage of the intermittent and fluctuating energy derived from renewable sources.

Circ-DONSON promotes malignant progression of glioma through modulating FOXO3

OBJECTIVE

The aim of this study was to investigate the expression level of circ-DONSON in glioma and to explore its effect on glioma metastasis and the underlying mechanism.

PATIENTS AND METHODS

Quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) was performed to examine circ-DONSON expression in 40 paired glioma tumor tissues and adjacent tissues. Meanwhile, the relation between circ-DONSON level and clinical parameters of glioma and the prognosis of patients was analyzed. The expression of circ-DONSON in glioma cell lines was analyzed by qRT-PCR as well. In addition, circs-DONSON silencing model was constructed in glioma cell lines. Cell counting kit-8 (CCK-8), cell scratch, and transwell migration assays were performed to investigate the effect of circ-DONSON on biological functions of glioma cells. Finally, the interplay between FOXO3 and circ-DONSON was explored.

RESULTS

QRT-PCR results revealed that the expression level of circ-DONSON in glioma tumor tissues was remarkably higher than that of adjacent tissues, and the difference was statistically significant (p<0.05). Compared with patients with low expression of circ-DONSON, significantly higher prevalence of lymph node or distant metastasis and worse prognosis were observed in patients with high expression of circ-DONSON (p<0.05). The proliferation and migration abilities of glioma cells in circ-DONSON silenced group were remarkably suppressed when compared with NC group (p<0.05). Additionally, FOXO3 expression was remarkably down-regulated in glioma cell lines and tissues. FOXO3 expression was negatively correlated with circ-DONSON expression. In addition, cell reverse experiment demonstrated that circ-DONSON and FOXO3 can regulate each other, thereby together affecting the malignant progression of glioma.

CONCLUSIONS

Circ-DONSON was remarkably associated with lymph node or distant metastasis, as well as poor prognosis of patients with glioma. Furthermore, it promoted the metastasis of glioma cells via regulating FOXO3.

Ultrathin Z-scheme 2D/2D N-doped HTiNbO5 nanosheets/g-C3N4 porous composites for efficient photocatalytic degradation and H2 generation under visible light

To realize highly efficient utilization of solar energy for solving problems of environmental pollution and energy shortage has attracted increasing attention. Herein, a two-step exfoliation-restacking process was employed to construct ultrathin Z-scheme two-dimensional (2D)/2D N-doped HTiNbO₅ nanosheets/g-C₃N₄ (RTCN) heterojunction composites with the increased specific surface areas, showing the enhanced photocatalytic performance for rhodamine B (RhB) degradation and hydrogen (H₂) generation under visible light irradiation. A 2D/2D heterojunction structure was formed between N-doped H⁺-restacked HTiNbO₅ nanosheets (N-RTNS) and g-C₃N₄, which was beneficial for the effectively spatial separation of photogenerated charge carriers. The improved photocatalytic activities may be attributed to the synergistic effects of the increased specific surface area, N-doping and 2D/2D heterostructure. The active species of holes (h⁺), hydroxyl (•OH) and superoxide (•O₂^-) radicals contributed to RhB photodegradation. A Z-scheme photocatalytic mechanism was proposed over RTCN-2 composite, showing dual advantages of the highly redox ability and efficient charge carrier separation.

Simple fabrication of Z-scheme MgIn2S4/Bi2WO6 hierarchical heterostructures for enhancing photocatalytic reduction of Cr(vi)

Direct Z-scheme MgIn2S4/Bi2WO6 hierarchical heterostructures were simply fabricated, exhibiting distinctly enhanced photocatalytic activity for Cr(vi) reduction under simulated sunlight irradiation.

Direct Z-scheme hierarchical heterostructures of oxygen-doped g-C3N4/In2S3 with efficient photocatalytic Cr(vi) reduction activity

Direct Z-scheme hierarchical heterostructures of O-doped g-C3N4/In2S3 were simply prepared, exhibiting efficient photocatalytic Cr(vi) reduction under visible light illumination.

Beyond C3N4 π-conjugated metal-free polymeric semiconductors for photocatalytic chemical transformations

Photocatalysis with stable, efficient and inexpensive metal-free catalysts is one of the most promising options for non-polluting energy production. This review article covers the state-of-the-art development of various effective metal-free polymeric photocatalysts with large π-conjugated units for chemical transformations including water splitting, CO2 and N2 reduction, organic synthesis and monomer polymerisation. The article starts with the catalytic mechanisms of metal-free photocatalysts. Then a particular focus is on the rational manipulation of π-conjugation enlargement, charge separation, electronic structures and band structures in the design of metal-free polymeric photocatalysts. Following the design principles, the selection and construction of functional units are discussed, as well as the connecting bonds and dimensions of π-conjugated polymeric photocatalysts. Finally the hot and emerging applications of metal-free polymeric photocatalysts for photocatalytic chemical transformations are summarized. The strategies provide potential avenues to address the challenges of catalyst activity, selectivity and stability in the further development of highly effective metal-free polymeric photocatalysts.

In situ construction of a 2D/2D heterostructured ZnIn2S4/Bi2MoO6Z-scheme system for boosting the photoreduction activity of Cr(vi)

The direct 2D/2D Z-scheme heterostructures of ZnIn₂S₄/Bi₂MoO₆ were rationally constructed, exhibiting obviously enhanced photocatalytic activity for Cr(vi) reduction under visible light (λ ≥ 420 nm) irradiation.

α-Fe2O3/Ag/CdS ternary heterojunction photoanode for efficient solar water oxidation

By taking full advantage of the α-Fe2O3/Ag/CdS ternary heterojunction in charge separation and transfer, light harvesting and electrocatalytic water oxidation, obviously improved water oxidation performance was achieved on the photoanode.

Silicon Photoanode Modified with Work-function-tuned Ni@Fey Ni1-y (OH)2 Core-Shell Particles for Water Oxidation

The photoelectrochemical (PEC) water splitting determines by the light absorption and charge extraction/injection. Here, we dispersedly modified the core-shell structured Ni@Ni_y Fe_1-y (OH)₂ on Si photoanodes and in-situ electrochemically converted it to Ni@Ni_y Fe_1-y OOH to form a Si/SiO_x /Ni@Ni_y Fe_1-y OOH assembly, exhibiting the adjustable band bending and catalytic ability in water oxidation depending closely on the composition of Ni_y Fe_1-y OOH. Combining with the island-like dispersed distribution to maximize the light absorption and the Ni@Ni_y Fe_1-y shell as a high work function and a catalytic layer to simultaneously enlarge charge extraction and injection, the Si/SiO_x /Ni@Ni_0.7 Fe_0.3 OOH assembly achieved an onset potential of 1.0 V_RHE , a saturated current density of 35.4 mA cm^-2 and a more than 50 h stability in an electrolyte with pH 9 under AM1.5G simulated sunlight irradiation. Our findings suggested that regulating the charge energetics at Si-electrolyte interface by discontinuously modifying a composition-adjustable core-shell structure is a potential route to develop highly efficient PEC devices.

A Capacitor-type Faradaic Junction for Direct Solar Energy Conversion and Storage

Two-electrode solar rechargeable devices trigger intense attention due to their potential applications in solar energy conversion and storage. However, interface energy barriers lead to severe loss of output voltage and negligible dark discharge current. Therefore, external biases are required for dark discharge in these devices, limiting their practical applications. Herein, we report a new two-electrode device of Si/WO₃ /H₂ SO_4(aq) /C that can work without bias. The device has the highest dark output power among all of the two-electrode solar rechargeable devices. The device based on a Si/WO₃ junction indicates photoinduced adjustable interface barrier height during charge transfer, which can overcome the energy barrier and realize dark discharge without bias. Owing to the interface characteristics, the Si/WO₃ is designated as a capacitor-type Faradaic junction.

Polaron States as a Massive Electron-Transfer Pathway at Heterojunction Interface

For heterojunction semiconductor photoelectrodes, efficient charge separation is localized in the junction-induced electric field region and charge transfer follows a band-to-band charge-transfer pathway. Here, we found that polaron states at the heterojunction interface have a function of storing and transferring electrons. As a successful demonstration, we verified that the polaron states (Ti³⁺OH) on TiO₂ are not passivated when used to create a CdS/TiO₂ heterojunction and function as an efficient pathway for massively capturing, storing, and transferring the electrons from conduction bands of both TiO₂ and CdS, thus effectively enhancing the charge separation efficiency of the heterojunction photoanode. The electron throughput of polaron states remains a positive correlation with polaron state density. Interfacial electron transfer through the TiO₂ surface polaron states has great potential application in the development of high-performance heterojunction devices based on TiO₂.