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Minisci reaction of heteroarenes and unactivated C(sp3)–H alkanes via a photogenerated chlorine radical from FeCl3 and seawater.

Comparison of the nanostructured Si photocathodes fabricated by chemical etching (c-Si), electrochemical etching (ec-Si) and photoelectrochemical etching (pec-Si) and their dramatically enhanced PEC water splitting.

This work demonstrated a regulable cross-coupling of alcohols with benzothiazole under visible light. Two kinds of products, alkyl- and acetyl-derived benzothiazoles, are achieved with high yields up to 99% in Ar and 90% in air, respectively.

A simple and mild photoredox catalytic approach to access difluoroalkylated dioxodibenzothiazepines in high regioselectivity via radical cascade cyclization has been described herein. In contrast to previous methods, this strategy does not involve the use of transition-metal catalysts and avoids the potential disadvantages of inevitable toxicity and the tedious removal process of metal catalysts. The commercially available and inexpensive CF2 precursors, wide substrate scope, and mild reaction conditions demonstrate the practicability of this approach.

Since the water oxidation half-reaction requires the transfer of multi-electrons and the formation of O-O bond, it's crucial to investigate the catalytic behaviours of semiconductor photoanodes. In this work, a bio-inspired copper-bipyridine catalyst of Cu(dcbpy) is decorated on the nanoporous Si photoanode (black Si, b-Si). Under AM1.5G illumination, the b-Si/Cu(dcbpy) photoanode exhibits a high photocurrent density of 6.31 mA cm

In contrast with the well-developed radical thiol-ene reaction to access anti-Markovnikov-type products, the research on the catalytic Markovnikov-selective hydrothiolation of alkenes is very restricted. Because of the catalyst poisoning of metal catalysts by organosulfur compounds, limited examples of transition-metal-catalyzed thiol-ene reactions have been reported. However, in this work, a directing-group-assisted hydrothiolation of styrenes with thiols by photoredox/cobalt catalysis is found to proceed smoothly to afford Markovnikov-type sulfides with excellent regioselectivity.

Cubic silicon carbide (3C-SiC) is a promising photoelectrode material for solar water splitting due to its relatively small band gap (2.36 eV) and its ideal energy band positions that straddle the water redox potentials. However, despite various coupled oxygen-evolution-reaction (OER) cocatalysts, it commonly exhibits a much smaller photocurrent (Funding Agencies|Swedish Research Council (Vetenskapsradet)Swedish Research Council [2018-04670, 202004400]; Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (FORMAS)Swedish Research Council Formas [2016-00559]; Swedish Foundation for International Cooperation in Research and Higher Education (STINT) [CH2016-6722]; AForsk foundation [19-311]

Inspired by the natural [NiFe]-H 2 ase , we designed mimic 1 , (dppe)Ni(m-pdt)(m-Cl)Ru(CO) 2 Cl, in order to realize effective H 2 evolution under photocatalytic conditions. However, a new species 2 was captured in the course of photo-, electro-, and chemo- one-electron reduction. Experimental studies of in-situ infrared spectroscopy (IR), electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), X-ray absorption spectroscopy (XAS), as well as density functional theory (DFT) calculations corroborated a dimeric structure of 2 as a closed-shell, symmetric structure with Ru I center. The isolated dimer 2 showed a real catalytic role in photocatalysis (TOF 1936 h -1 ) for H 2 evolution. The remarkable catalytic activity and unique dimer structure of 2 operated in photocatalysis unveiled a broad research prospect in heterobinuclear mimics for advanced H 2 evolution.

A surface-nanostructured semiconductor photoelectrode is highly desirable for photo-electrochemical (PEC) solar-to-fuel production due to its large active surface area, efficient light absorption, and significantly reduced distance for charge transport. Here, we demonstrate a facile approach to fabricate a nanoporous 6H-silicon carbide (6H-SiC) photoanode with a conformal coating of Ni-FeOOH nanorods as a water oxidation cocatalyst. Such a nanoporous photoanode shows significantly enhanced photocurrent density (j(ph)) with a zero-onset potential. A dendritic porous 6H-SiC with densely arranged holes with a size of similar to 40 nm on the surface is fabricated by an anodization method, followed by the hydrothermal deposition of FeOOH nanorods and electrodeposition of NiOOH. Under an illumination of AM1.5G 100 mW/cm(2), the Ni-FeOOH-coated nanoporous 6H-SiC photoanode exhibits an onset potential of 0 V versus the reversible hydrogen electrode (V-RHE) and a high j(ph) of 0.684 mA/cm(2) at 1 V-RHE, which is 342 times higher than that of the Ni-FeOOH-coated planar 6H-SiC photoanode. Moreover, the nanoporous photoanode shows a maximum applied-bias-photon-to-current efficiency (ABPE) of 0.58% at a very low bias of 0.36 V-RHE, distinctly outperforming the planar counterpart. The impedance measurements demonstrate that the nanoporous photoanode possesses a significantly reduced charge-transfer resistance, which explains the dramatically enhanced PEC water-splitting performance. The reported approach here can be widely used to fabricate other nanoporous semiconductors for solar energy conversion. Funding Agencies|Swedish Research Council (Vetenskapsradet)Swedish Research Council [621-2014-5461, 2018-04670]; Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (FORMAS)Swedish Research Council Formas [2016-00559]; Swedish Foundation for International Cooperation in Research and Higher Education (STINT) [CH2016-6722]; AForsk foundation [16-399]; Stiftelsen Olle Engkvist ByggmastareSwedish Research Council [189-0243]; China Scholarship CouncilChina Scholarship Council [201706400041]

Photoelectrochemical (PEC) water-splitting offers a promising method to convert the intermittent solar energy into renewable and storable chemical energy. However, the most studied semiconductors generally exhibit a poor PEC performance including low photocurrent, small photovoltage, and/or large onset potential. In this work, we demonstrate a significant enhancement of photovoltage and photocurrent together with a substantial decrease of onset potential by introducing electrocatalytic and p-type NiO nanoclusters on an n-type cubic silicon carbide (3C-SiC) photoanode. Under AM1.5G 100 mW cm(-2) illumination, the NiO-coated 3C-SiC photoanode exhibits a photocurrent density of 1.01 mA cm(-2) at 0.55 V versus reversible hydrogen electrode (V-RHE), a very low onset potential of 0.20 V-RHE and a high fill factor of 57% for PEC water splitting. Moreover, the 3C-SiC/NiO photoanode shows a high photovoltage of 1.0 V, which is the highest value among reported photovoltages. The faradaic efficiency measurements demonstrate that NiO also protects the 3C-SiC surface against photo-corrosion. The impedance measurements evidence that the 3C-SiC/NiO photoanode facilitates the charge transfer for water oxidation. The valence-band position measurements confirm the formation of the 3C-SiC/NiO p-n heterojunction, which promotes the separation of the photogenerated carriers and reduces carrier recombination, thus resulting in enhanced solar water-splitting. Funding Agencies|Swedish Research Council (Vetenskapsradet) [621-2014-5461, 2018-04670, 621-2014-5825]; Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (FORMAS) [2016-00559]; Swedish Foundation for International Cooperation in Research and Higher Education (STINT) [CH2016-6722]; AForsk Foundation [16-399]; Stiftelsen Olle Engkvist Byggmastare [189-0243]; EU project CHALLENGE; Knut and Alice Wallenberg Foundation [KAW 2014.0276]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO Mat LiU) [2009 00971]

To achieve high-efficiency deep-blue electroluminescence satisfying Rec.2020 standard blue gamut, two thermally activated delayed fluorescent (TADF) emitters are developed: 5-(2,12-di-tert-butyl-5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracen-7-yl)-10,10-diphenyl-5,10-dihydrodibenzo[b,e][1,4]azasiline (TDBA-PAS) and 10-(2,12-di-tert-butyl-5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracen-7-yl)-9,9-diphenyl-9,10-dihydroacridine (TDBA-DPAC). Inheriting from their parented organoboron multi-resonance core, both emitters show very promising deep-blue emissions with relatively narrow full width at half-maximum (FWHM, ≈50 nm in solution), high photoluminescence quantum yield (up to 92.3%), and short emission lifetime (≤2.49 µs) with fast reverse intersystem crossing (10

Inspired by the natural [NiFe]-H

The paucity of research on hydrogen evolution reaction (HER) under neutral conditions, which is a more sustainable way to produce H-2 compared to acidic and alkaline HER, encourages the development of efficient catalytic materials and devices and deeper investigation of the mechanisms behind neutral HER. We present an electrode concept for facilitating HER under neutral conditions. The concept entails the use of annealing-reshaped silver (Ag) nanoparticle array on monolayer epitaxial graphene (MEG) on 4H-SiC. Measurements of HER performance show more positive onset potential of the cathodic HER for Ag-decorated MEG compared to that for pristine MEG, indicating improved water dissociation at Ag/MEG electrodes. Complementary morphological characterization, absorption measurements, and Raman mapping analysis enable us to ascribe the enhanced catalytic performance of electrodes decorated with 2 nm thick annealed Ag on the synergetic effect originating from simultaneous water reduction on circular Ag nanoparticles of 31 nm in diameter and on compressively strained Ag-free graphene regions. The overall results pave the way toward development of stable van der Waals heterostructure electrodes with a tunable metal-carbon interaction for fast HER under neutral conditions. (C) 2021 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). Funding Agencies|Angpanneforeningens Forskningsstiftelse [16-541, 21-112]; VRSwedish Research Council [2018-04962, 2016-05362]; Swedish Research Council (Vetenskapsradet)Swedish Research Council [2018-04670, 2020-04400]; AForsk foundation [19-311]; FCT/MEC [UIDB/50025/2020, UIDP/50025/2020]

There is an increasing demand to solve the environmental dissemination problems of fluorosurfactants and improve their responsive behavior, surface properties, chemical stability and foaming performance. In this work, three pH-responsive fluorosurfactants, named F9-es-mor, F9-N3-mor and F9-N2-mor, were synthesized by facile one-step esterification or amidation. The F9-N2-mor efficiently reduced the water surface tension to 14.56 mN·m−1 with a low critical micelle concentration (CMC) of 0.20 mM. More importantly, both F9-N2-mor and F9-N3-mor obviously displayed reproducible pH-response foaming behaviors at an optimal pH of 6.0 and 8.0, respectively, probably owing to their rigid molecular structure, strong intermolecular H-bond and high membrane elasticity. Besides, the morpholine fluorosurfactants defoam at pH below 4.0, indicating that these fluorosurfactants could be recycled and their residue could be easily removed. Overall, the novel fluorosurfactants F9-N2-mor might provide new inspiration to recycle fluorosurfactants as well as construct pH-responsive foams.

Of paramount significance in phosphorescent organic light‐emitting diodes (PHOLEDs) are the facts that Förster resonance energy transfer (FRET) must be sufficient and back energy transfer should be prohibited. Herein, the FRET efficiencies for high‐performance PHOLEDs based on a simple bipolar luminogen 1‐phenyl‐2‐(5′‐phenyl‐[1,1′:3′,1″‐terphenyl]‐4‐yl)‐1H‐phenanthro[9,10‐d]imidazole (PHT‐PPI) with high triplet energy of 2.44 eV are systematically investigated. As a result, with PO‐01 as dopant, the high‐performance orange PHOLED is achieved with maximum external quantum efficiency (EQEmax) of 26.14% and ultrahigh brightness of 152 000 cd m−2, which are the highest reported efficiencies for orange OLEDs with such high brightness. In addition, the green and red PHOLEDs are also fabricated with EQEmax of 15.38% and 16.12%, respectively. Furthermore, the nondoped device based on PHT‐PPI as a deep‐blue emitter is also obtained with an EQEmax of 5.12% and the Commission Internationale de L’Eclairage (CIE) index of (0.15, 0.08). More importantly, the blue, green, orange, and red devices exhibit low efficiency roll‐off, particularly, of which the orange PHOLED is extremely small (

A simple [FeFe]-hydrogenase mimic, Fe2S2(CO)6, was integrated with CdSe quantum dots to form a sensitized electrode on a p-NiO layer, which can start to catalyze proton reduction at a bias voltage as positive as ≈0.3 V (vs. NHE) in neutral water. The result provides a promising way to overcome the much more negative onset bias of [FeFe]-hydrogenase mimics for H2 evolution under mild conditions.

Two water soluble [FeFe]-hydrogenase ([FeFe]-H2ase) mimics, Fe2S2-2SO3Na (1) and Fe2S2-SO3Na (2), were designed to compare the performance of photocatalytic H2 evolution systems using quantum dots (QDs) and the molecular photosensitizer [Ru(bpy)3]2+ in water. Under the same conditions, the resulting systems showed that CdSe QDs display much higher activity than [Ru(bpy)3]2+, meanwhile, the turnover numbers (TONs) of 2.65 × 104 (1) and 1.88 × 104 (2) for CdSe QD systems and 178 (1) and 114 (2) for [Ru(bpy)3]2+ systems were comparable with the highest reported H2 evolution systems using the same photosensitizers. Spectroscopic and electrochemical analyses revealed that the excited [Ru(bpy)3]2+ undergoes reductive-quenching while the excited CdSe QDs proceed via oxidative-quenching during the catalytic process. The greater free energy change and faster electron transfer rate in the CdSe QD system made the electron transfer between the photosensitizer and [FeFe]-H2ase mimics more efficient, which was subsequently corroborated by emission quenching and transient absorption experiments. The reduced [FeFe]-H2ase mimics generated from the CdSe QDs were demonstrated to react with protons at a rate of 1.17 × 107 M−1 s−1 for 1 and 8.62 × 106 M−1 s−1 for 2.

[FeFe]‐hydrogenase ([FeFe]‐H2ase) mimics, inspired by hydrogenases in nature, have emerged as an important class of molecular catalysts toward hydrogen (H2) evolution. Here, a per‐6‐thiol‐cyclodextrin (CDSH) engineered [FeFe]‐H2ase mimic/CdSe quantum dot assembly is established for effective photocatalytic H2 evolution. In the assembly, CDSH is firstly anchored on CdSe QDs via the strong multidentate Cd‐thiol coordination. Then, [FeFe]‐H2ase mimic is assembled on the QD surface via the host‐guest supramolecular interaction between the hydrophobic cavity of cyclodextrin (CD) and the adamantly (AD) group of [FeFe]‐H2ase mimic. In neutral aqueous solution of isopropanol, the Fe2S2‐AD/CDSH/CdSe assembly exhibits a turnover number (TON) of 1.12 × 105 (based on Fe2S2‐AD) under visible light, which is about 12‐fold to the corresponding system without CDSH. Mechanistic insights indicate that CDSH can not only prevent the aggregation of QDs in acidic conditions, but also balance the interfacial charge (electron and hole) transfer to avoid the photocorrosion of QDs, thereby giving the highest TON of H2 photogeneration based on [FeFe]‐H2ase mimics up to date. This article is protected by copyright. All rights reserved.

Solar water splitting based on semiconductor photoelectrodes is a promising route to convert solar energy into renewable hydrogen fuel. Since the pioneering work of photoelectrochemical (PEC) systems in 1972, a large variety of semiconductors such as oxides, sulfides, phosphides, and silicon have been studied in the context of PEC water splitting configuration. Among them, silicon carbide (SiC) exhibits an excellent energy band structure that straddles the water redox potentials. In particular, cubic SiC (3C-SiC), with a suitable bandgap of 2.36 eV, is favorable for visible sunlight absorption. Recently, 3C-SiC has attracted much interest in PEC water splitting. In this review, the progress, challenges, and prospects of using SiC for PEC water splitting are summarized. Funding Agencies|Swedish Research Council (Vetenskapsradet)Swedish Research Council [621-2014-5461, 2018-04670]; Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (FORMAS)Swedish Research Council Formas [2016-00559]; Swedish Foundation for International Cooperation in Research and Higher Education (STINT) [CH2016-6722]; AForsk Foundation [19-311]; Stiftelsen Olle Engkvist ByggmastareSwedish Research Council [189-0243]

Nature uses hydrogenase enzyme to catalyze proton reduction at pH 7 with overpotentials and catalytic efficiencies that rival platinum electrodes. Over the past several years, [FeFe]-hydrogenase ([FeFe]-H2 ase) mimics have been demonstrated to be effective catalysts for light-driven H2 evolution. However, it remains a significant challenge to realize H2 production by such an artificial photosynthetic system in neutral aqueous solution. Herein, we report a new system for photocatalytic H2 evolution working in a broad pH range, especially under neutral conditions. This unique system is consisted of branched polyethylenimine (PEI)-grafted [FeFe]-H2 ase mimic (PEI-g-Fe2 S2 ), MPA-CdSe quantum dots (MPA=mercaptopropionic acid), and ascorbic acid (H2 A) in water. Due to the secondary coordination sphere of PEI, which has high buffering capacity and stabilizing ability, the system is able to produce H2 under visible-light irradiation with turnover number of 10 600 based on the Fe2 S2 active site in PEI-g-Fe2 S2 . The stability and activity are much better than that of the same system under acidic or basic conditions and they are, to the best of our knowledge, the highest known to date for photocatalytic H2 evolution from a [FeFe]-H2 ase mimic in neutral aqueous solution.

Achieving highly efficient hydrogen (H2) evolution via artificial photosynthesis is a great ambition pursued by scientists in recent decades because H2 has high specific enthalpy of combustion and benign combustion product. [FeFe]-Hydrogenase ([FeFe]-H2ase) mimics have been demonstrated to be promising catalysts for H2 photoproduction. However, the efficient photocatalytic H2 generation system, consisting of PAA-g-Fe2S2, CdSe QDs and H2A, suffered from low stability, probably due to the hole accumulation induced photooxidation of CdSe QDs and the subsequent crash of [FeFe]-H2ase mimics. In this work, we take advantage of supramolecular interaction for the first time to construct the secondary coordination sphere of electron donors (HA−) to CdSe QDs. The generated secondary coordination sphere helps realize much faster hole removal with a ~30-fold increase, thus leading to higher stability and activity for H2 evolution. The unique photocatalytic H2 evolution system features a great increase of turnover number to 83600, which is the highest one obtained so far for photocatalytic H2 production by using [FeFe]-H2ase mimics as catalysts.

A variety of benzothiazoles is obtained by an intramolecular oxidative photocyclization of corresponding N-arylthioamides.

An external oxidant-free oxidative coupling for aromatic C–H thiolation by visible-light photoredox cobalt-catalysis has been developed. Various substrates could afford benzothiazoles in good to excellent yields, and only H2 is generated as a side product. When catalytic TBAOH was used as the base, not only 2-aryl but also 2-alkylbenzothiazoles could be obtained through this novel dehydrogenative coupling reaction. This method could be scaled up and applied to the synthesis of biologically active molecules bearing benzothiazole structural scaffolds (potent antitumor agents). Furthermore, the unexpected oxidation byproduct amides, which are often generated in oxidative cyclization of thiobenzanilides, can be completely avoided. Mechanistic studies showed that the H2 originates from the substrates. The kinetic studies indicate that the interaction between the cobalt catalyst and proton might be involved in the rate-limiting process.

Nature has created [FeFe]-hydrogenase enzyme as a hydrogen-forming catalyst with a high turnover rate. However, it does not meet the demands of economically usable catalytic agents because of its limited stability and the cost of its production and purification. Synthetic chemistry has allowed the preparation of remarkably close mimics of [FeFe]-hydrogenase but so far failed to reproduce its catalytic activity. Most models of the active site represent mimics of the inorganic cofactor only, and the enzyme-like reaction that proceeds within restricted environments is less well understood. Here we report that chitosan, a natural polysaccharide, improves the efficiency and durability of a typical mimic of the diiron subsite of [FeFe]-hydrogenase for photocatalytic hydrogen evolution. The turnover number of the self-assembling system increases ~4,000-fold compared with the same system in the absence of chitosan. Such significant improvements to the activity and stability of artificial [FeFe]-hydrogenase-like systems have, to our knowledge, not been reported to date.