A p‑n‑p Configuration Based on the Cuprous Oxide/Silicon Tandem Photocathode for Accelerating Solar-Driven Hydrogen Evolution

Photoelectrochemical splitting of water into hydrogen is a potential route to motivate the application of solar-driven conversion to clean energy but is regularly limited by its low efficiency. The key to addressing this issue is to design a suitable photocathode configuration for high-efficiency photogenerated carrier separation and transmission to photocathode-surface reaction sites. In this work, we report a Si-Cu2O tandem photocathode featuring a p-n-p configuration for solar-driven hydrogen evolution in an alkaline solution. Driven by this built-in field, the electrons induced from Si were transferred through FeOOH, which acted as electron tunnels, to combine with the holes from Cu2O, triggering more electrons generated from Cu2O to particiate in the surface reaction. Under simulated sunlight, the optimized photocathode achieved and maintained a photocurrent density of −11 mA/cm2 at 0 VRHE in alkaline conditions for 120 min, outperforming the reported tandem cell consisting of Si and Cu2O photocathodes. Our results provide valuable insight into a feasible way to construct an optimized photocathode for efficient solar-driven H2 evolution

Rh(III)-Catalyzed Decarboxylative <i>ortho</i>-Heteroarylation of Aromatic Carboxylic Acids by Using the Carboxylic Acid as a Traceless Directing Group

Highly selective decarboxylative <i>ortho</i>-heteroarylation of aromatic carboxylic acids with various heteroarenes has been developed through Rh­(III)-catalyzed two-fold C–H activation, which exhibits a wide substrate scope of both aromatic carboxylic acids and heteroarenes. The use of naturally occurring carboxylic acid as the directing group avoids troublesome extra steps for installation and removal of an external directing group

Rhodium-Catalyzed Oxidative Coupling of Benzoic Acids with Terminal Alkynes: An Efficient Access to 3‑Ylidenephthalides

Herein we disclose the first example of transition-metal-catalyzed oxidative coupling/annulation of simple benzoic acids with terminal alkynes via C–H activation. A range of aromatic carboxylic acids and terminal alkynes have been found to be viable substrates in this reaction, providing a simple and efficient method for the synthesis of diverse 3-ylidenephthalides with complete <i>Z</i> selectivity

Rhodium-Catalyzed Oxidative Coupling of Benzoic Acids with Terminal Alkynes: An Efficient Access to 3‑Ylidenephthalides

Herein we disclose the first example of transition-metal-catalyzed oxidative coupling/annulation of simple benzoic acids with terminal alkynes via C–H activation. A range of aromatic carboxylic acids and terminal alkynes have been found to be viable substrates in this reaction, providing a simple and efficient method for the synthesis of diverse 3-ylidenephthalides with complete <i>Z</i> selectivity

Unparalleled Ease of Access to a Library of Biheteroaryl Fluorophores via Oxidative Cross-Coupling Reactions: Discovery of Photostable NIR Probe for Mitochondria

The development of straightforward accesses to organic functional materials through C–H activation is a revolutionary trend in organic synthesis. In this article, we propose a concise strategy to construct a large library of donor–acceptor-type biheteroaryl fluorophores via the palladium-catalyzed oxidative C–H/C–H cross-coupling of electron-deficient 2<i>H</i>-indazoles with electron-rich heteroarenes. The directly coupled biheteroaryl fluorophores, named Indazo-Fluors, exhibit continuously tunable full-color emissions with quantum yields up to 93% and large Stokes shifts up to 8705 cm^–1 in CH₂Cl₂. By further fine-tuning of the substituent on the core skeleton, Indazo-Fluor <b>3l</b> (FW = 274; λ_em = 725 nm) is obtained as the lowest molecular weight near-infrared (NIR) fluorophore with emission wavelength over 720 nm in the solid state. The NIR dye <b>5h</b> specifically lights up mitochondria in living cells with bright red luminescence. Typically, commercially available mitochondria trackers suffer from poor photostability. Indazo-Fluor <b>5h</b> exhibits superior photostability and very low cytotoxicity, which would be a prominent reagent for <i>in vivo</i> mitochondria imaging

Unparalleled Ease of Access to a Library of Biheteroaryl Fluorophores via Oxidative Cross-Coupling Reactions: Discovery of Photostable NIR Probe for Mitochondria

The development of straightforward accesses to organic functional materials through C–H activation is a revolutionary trend in organic synthesis. In this article, we propose a concise strategy to construct a large library of donor–acceptor-type biheteroaryl fluorophores via the palladium-catalyzed oxidative C–H/C–H cross-coupling of electron-deficient 2<i>H</i>-indazoles with electron-rich heteroarenes. The directly coupled biheteroaryl fluorophores, named Indazo-Fluors, exhibit continuously tunable full-color emissions with quantum yields up to 93% and large Stokes shifts up to 8705 cm^–1 in CH₂Cl₂. By further fine-tuning of the substituent on the core skeleton, Indazo-Fluor <b>3l</b> (FW = 274; λ_em = 725 nm) is obtained as the lowest molecular weight near-infrared (NIR) fluorophore with emission wavelength over 720 nm in the solid state. The NIR dye <b>5h</b> specifically lights up mitochondria in living cells with bright red luminescence. Typically, commercially available mitochondria trackers suffer from poor photostability. Indazo-Fluor <b>5h</b> exhibits superior photostability and very low cytotoxicity, which would be a prominent reagent for <i>in vivo</i> mitochondria imaging

Novel Ruthenium Sensitizers with a Phenothiazine Conjugated Bipyridyl Ligand for High-Efficiency Dye-Sensitized Solar Cells

Two efficient ruthenium sensitizers with a phenothiazine-modified bipyridine as an ancillary ligand, coded <b>SCZ-1</b> and <b>SCZ-2</b>, have been developed as dyes in dye-sensitized solar cells (DSSCs). Both sensitizers exhibit low-energy metal-to-ligand charge transfer (MLCT) bands centered at 539 nm with high molar extinction coefficients of 1.77 × 10⁴ M^–1 cm^–1 for <b>SCZ-1</b> and 1.66 × 10⁴ M^–1 cm^–1 for <b>SCZ-2</b>, which are significantly higher than the corresponding value for the reference <b>N719</b> (1.27 × 10⁴ M^–1 cm^–1), indicating that the light-harvesting capacity of ruthenium sensitizers can be reinforced by introducing phenothiazine moieties into the bipyridine ligand. Under AM 1.5G irradiation (100 mW cm^–2), <b>SCZ</b>-<b>1</b> and <b>SCZ-2</b> sensitized DSSC devices show impressive power conversion efficiencies (PCE) up to 10.4% by using of iodide-based electrolytes, which exceeds that of <b>N719</b> (9.9%) under the same conditions. Both of the open circuit voltage (<i>V</i>_OC) and fill factor (FF) of <b>SCZ</b>-sensitized solar cells approximate to those of <b>N719</b>-sensitized cell. The relatively higher efficiencies of the <b>SCZ</b>-sensitized cells than that of <b>N719</b>-sensitized cell come from their higher short-circuit photocurrent density (<i>J</i>_SC), which may be mainly attributed to the high absorption coefficient. The absorption spectrum and device efficiency of <b>SCZ-1</b> are both quite close to those of <b>SCZ-2</b>, suggesting that the difference in alkyl chains on the N atom of phenothiazine is not a decisive factor in affecting the photovoltaic performance of dyes

Nanoporous Fe-Based Alloy Prepared by Selective Dissolution: An Effective Fenton Catalyst for Water Remediation

A fully nanoporous Fe-rich alloy, prepared by selective dissolution of melt-spun Fe_43.5Cu_56.5 ribbons, exhibits outstanding properties as a heterogeneous Fenton catalyst toward the degradation of methyl orange (MO) in aqueous solution. In addition, the ferromagnetic characteristics of this material enable its wireless manipulation toward specific locations within polluted wastewater. The influence of selective dissolution on the microstructure, sample morphology (surface and cross-section), elemental composition, and magnetic properties of the resulting nanoporous alloy is investigated. The dealloying procedure enhances the saturation magnetization and drastically increases the catalytic performance (i.e., the time required for full degradation of MO from the medium is reduced by a factor of approximately 2 by subjecting the Fe_43.5Cu_56.5 ribbons to prior dealloying). Remarkably, the effectiveness of this nanoporous material surpasses the results obtained by the homogeneous Fenton reaction using an equivalent concentration of Fe cations leached into the media from the nanoporous alloy. The different factors that promote the high catalytic activity are discussed. The outstanding catalytic activity, together with the simplicity of the synthetic procedure, makes this material very appealing for water remediation using advanced Fenton processes

Molecular Engineering of Mechano­chromic Materials by Programmed C–H Arylation: Making a Counterpoint in the Chromism Trend

The development of facile methods for screening organic functional molecules through C–H bond activation is a revolutionary trend in materials research. The prediction of mechano­chromism as well as mechano­chromic trends of luminogens is an appealing yet challenging puzzle. Here, we present a strategy for the design of mechano­chromic luminogens based on the dipole moment of donor–acceptor molecules. For this purpose, a highly efficient route to 2,7-diaryl-[1,2,4]­triazolo­[1,5-<i>a</i>]­pyrimidines (2,7-diaryl-TAPs) has been established through programmed C–H arylation, which unlocks a great opportunity to rapidly assemble a library of fluorophores for the discovery of mechano­chromic regularity. Molecular dipole moment can be employed to explain and further predict the mechano­chromic trends. The 2,7-diaryl-TAPs with electron-donating groups on the 2-aryl and electron-withdrawing groups on the 7-aryl possess a relatively small dipole moment and exhibit a red-shifted mechano­chromism. When the two aryls are interchanged, the resulting luminogens have a relatively large dipole moment and display a blue-shifted mechano­chromism. Seven pairs of isomers with opposite mechano­chromic trends are presented as illustrative examples. The aryl-interchanged congeners with a bidirectional emission shift are structurally similar, which provides an avenue for understanding in-depth the mechano­chromic mechanism

Molecular Engineering of Mechano­chromic Materials by Programmed C–H Arylation: Making a Counterpoint in the Chromism Trend

The development of facile methods for screening organic functional molecules through C–H bond activation is a revolutionary trend in materials research. The prediction of mechano­chromism as well as mechano­chromic trends of luminogens is an appealing yet challenging puzzle. Here, we present a strategy for the design of mechano­chromic luminogens based on the dipole moment of donor–acceptor molecules. For this purpose, a highly efficient route to 2,7-diaryl-[1,2,4]­triazolo­[1,5-<i>a</i>]­pyrimidines (2,7-diaryl-TAPs) has been established through programmed C–H arylation, which unlocks a great opportunity to rapidly assemble a library of fluorophores for the discovery of mechano­chromic regularity. Molecular dipole moment can be employed to explain and further predict the mechano­chromic trends. The 2,7-diaryl-TAPs with electron-donating groups on the 2-aryl and electron-withdrawing groups on the 7-aryl possess a relatively small dipole moment and exhibit a red-shifted mechano­chromism. When the two aryls are interchanged, the resulting luminogens have a relatively large dipole moment and display a blue-shifted mechano­chromism. Seven pairs of isomers with opposite mechano­chromic trends are presented as illustrative examples. The aryl-interchanged congeners with a bidirectional emission shift are structurally similar, which provides an avenue for understanding in-depth the mechano­chromic mechanism