Unraveling the selectivity puzzle: To reconcile the experimental and computational discrepancy of CO₂ reduction to HCOOH and CO on Pb and Ag catalyst, we have incorporated solvation effects in our combined DFT/microkinetic study. Explicit solvation has a significant impact on reaction intermediate adsorption energies, resulting in CO selectivity on Ag and HCOOH selectivity on Pb surfaces, consistent with experimental findings.

Abstract

Herein, a comprehensive computational study of the impact of solvation on the reduction reaction of CO₂ to formic acid (HCOOH) and carbon monoxide on Pb(100) and Ag(100) surfaces is presented. Results further the understanding of how solvation phenomena influence the adsorption energies of reaction intermediates. We applied an explicit solvation scheme harnessing a combined density functional theory (DFT)/microkinetic modeling approach for the CO₂ reduction reaction. This approach reveals high selectivities for CO formation at Ag and HCOOH formation on Pb, resolving the prior disparity between ab initio calculations and experimental observations. Furthermore, the detailed analysis of adsorption energies of relevant reaction intermediates shows that the total number of hydrogen bonds formed by HCOO plays a primary role for the adsorption strength of intermediates and the electrocatalytic activity. Results emphasize the importance of explicit solvation for adsorption and electrochemical reaction phenomena on metal surfaces.

Co-based molecular photocatalysts: Nanosecond optical and X-ray absorption spectroscopy with theoretical calculations reveal a complete mechanistic pathway followed by 3 Co-based photocatalysts in pure water and show that the protonation of the Co^I intermediate can be enhanced through introduction of terminal hydrogen containing amine substituents that function as efficient proton relays.

Abstract

Nanosecond time-resolved X-ray (tr-XAS) and optical transient absorption spectroscopy (OTA) are applied to study 3 multimolecular photocatalytic systems with [Ru(bpy)₃]²⁺photoabsorber, ascorbic acid electron donor and Co catalysts with methylene (1), hydroxomethylene (2) and methyl (3) amine substituents in pure water. OTA and tr-XAS of 1 and 2 show that the favored catalytic pathway involves reductive quenching of the excited photosensitizer and electron transfer to the catalyst to form a Co^II square pyramidal intermediate with a bonded aqua molecule followed by a Co^I square planar derivative that decays within ≈8 μs. By contrast, a Co^I square pyramidal intermediate with a longer decay lifetime of ≈35 μs is formed from an analogous Co^II geometry for 3 in H₂O. These results highlight the protonation of Co^I to form the elusive hydride species to be the rate limiting step and show that the catalytic rate can be enhanced through hydrogen containing pendant amines that act as H−H bond formation proton relays.

Visible-light-induced halide-exchange between halide perovskite and organohalide solvents has been studied in which photo-induced electron-transfer from CsPbBr3 nanocrystals (NCs) to dihalomethane solvent molecules produces halide anions via reductive dissociation, followed by a spontaneous anion-exchange. Photo-generated holes in this process are less focused. Here, for CsPbBr3 in dibromomethane (DBM), we discover that Br radical (Br•) is a key intermediate resulting from the hole-oxidation. We successfully trapped Br• with reported methods and found that Br• is in continuous generation in DBM under visible light irradiation, hence imperative for catalytic reaction design. Continuous Br• within this halide-exchange process is active for photocatalytic [3+2] cycloaddition for vinylcyclopentane synthesis, a privileged scaffold in medicinal chemistry, with good yield and rationalized diastereoselectivity. The NCs photocatalyst is highly recyclable due to Br-based self-healing, leading to a particularly economic and neat heterogeneous reaction where the solvent DBM also behaves as a co-catalyst for perovskite photocatalysis. Halide perovskites, notable for efficient solar energy conversion, herein are demonstrated as an exceptional photocatalyst for Br radical-mediated [3+2] cycloaddition. We envisage such perovskite-induced Br radical strategy may serve as a powerful chemical tool to develop valuable halogen radical-involved reactions.

Organic electrode: 1,5-poly(anthraquinonylsulfide) (PAQS) is evaluated as cathode material for calcium batteries. It is demonstrated that the practical performance of the PAQS cathode is governed by the employed anode. Replacing the Ca metal anode with a calcium-tin (Ca _x Sn) alloy anode gave rise to significantly increased cycle life. With the as-prepared Ca _x Sn anode, the PAQS cathode could be cycled at 0.5C (1C=226 mAh g⁻¹) for 1000 cycles with a capacity retention of 45 mAh g⁻¹.

Abstract

Calcium (Ca) batteries are attractive post-lithium battery technologies, due to their potential to provide high-voltage and high-energy systems in a sustainable manner. We investigated herein 1,5-poly(anthraquinonylsulfide) (PAQS) for Ca-ion storage with calcium tetrakis(hexafluoroisopropyloxy)borate Ca[B(hfip)₄]₂ [hfip=OCH(CF₃)₂] electrolytes. It is demonstrated that PAQS could be synthesized in a cost-effective approach and be processed environmentally friendly into the electrodes. The PAQS cathodes could provide 94 mAh g⁻¹ capacity at 2.2 V vs. Ca at 0.5C (1C=225 mAh g⁻¹). However, cycling of the cells was severely hindered due to the fast degradation of the metal anode. Replacing the Ca metal anode with a calcium-tin (Ca−Sn) alloy anode, the PAQS cathodes exhibited long cycling performance (45 mAh g⁻¹ at 0.5C after 1000 cycles) and superior rate capability (52 mAh g⁻¹ at 5C). This is mainly ascribed to the flexible structure of PAQS and good compatibility of the alloy anodes with the electrolyte solutions, which allow reversible quinone carbonyl redox chemistry in the Ca battery systems. The promising properties of PAQS indicate that further exploration of the organic cathode materials could be a feasible direction towards green Ca batteries.

Deep eutectic solvents (DESs) appeared as an alternative to harmful organic solvents. This review presents a framework for understanding the development process of DESs, starting from the main parameters for judiciously selecting the DES components, then highlighting the methods of preparation and characterization, and ending with explaining the role of DESs in designing drug delivery systems.

Abstract

In the spirit of circular economy and sustainable chemistry, the use of environmentally friendly chemical products in pharmacy has become a hot topic. In recent years, organic solvents have been the subject of a great range of restriction policies due to their harmful effects on the environment and toxicity to human health. In parallel, deep eutectic solvents (DESs) have emerged as suitable greener solvents with beneficial environmental impacts and a rich palette of physicochemical advantages related to their low cost and biocompatibility. Additionally, DESs can enable remarkable solubilizing effect for several active pharmaceutical ingredients (APIs), thus forming therapeutic DESs (TheDESs). In this work, special attention is paid to DESs, presenting a precise definition, classification, methods of preparation, and characterization. A description of natural DESs (NaDESs), i. e., eutectic solvents present in natural sources, is also reported. Moreover, the present review article is the first one to detail the different approaches for judiciously selecting the constituents of DESs in order to minimize the number of experiments. The role of DESs in the biomedical and pharmaceutical sectors and their impact on the development of successful therapies are also discussed.

Advanced ZnO/ZnCr₂O₄ photocatalysts derived from ZnCr-layered double hydroxide (ZnCr-LDH) precursors are successfully synthetized by a simple thermal process. The optimized ZnO/ZnCr₂O₄ exhibit a considerable ammonia photosynthesis rate of 31.7 μmol g⁻¹ h⁻¹ in pure water, with the origin of the high activity being derived from the high-efficiency carrier separation due to the abundant interfaces.

Abstract

Drawing inspiration from the enzyme nitrogenase in nature, researchers are increasingly delving into semiconductor photocatalytic nitrogen fixation due to its similar surface catalytic processes. Herein, we reported a facile and efficient approach to achieving the regulation of ZnO/ZnCr₂O₄ photocatalysts with ZnCr-layered double hydroxide (ZnCr-LDH) as precursors. By optimizing the composition ratio of Zn/Cr in ZnCr-LDH to tune interfaces, we can achieve an enhanced nitrogen photofixation performance (an ammonia evolution rate of 31.7 μmol g⁻¹ h⁻¹ using pure water as a proton source) under ambient conditions. Further, photo-electrochemical measurements and transient surface photovoltage spectroscopy revealed that the enhanced photocatalytic activity can be ascribed to the effective carrier separation efficiency, originating from the abundant composite interfaces. This work further demonstrated a promising and viable strategy for the synthesis of nanocomposite photocatalysts for nitrogen photofixation and other challenging photocatalytic reactions.

5-Hydroxymethylfurfural (5-HMF) is regarded as one of the most promising platform feedstocks for producing valuable chemicals, fuels, and materials. In this study, we present a controllable fluorination technique for biomass-based 5-HMF and its oxygenated derivatives. This technique allows us to synthesize mono-fluoromethyl, difluoromethyl, and acylfluoro-substituted furan compounds by adjusting experimental conditions such as different fluorine sources and mole ratio. To gain a deeper understanding the reactivity order, we conducted intermolecular and  intramolecular competition experiments. The results revealed that the hydroxyl group exhibited the highest reactivity, followed by the aldehyde group. This finding provides important theoretical support and opens up the possibility of selective fluorination. The reaction offers several advantages, including mild conditions, no need for inert gas protection, and easy operation. Furthermore, the fluoro-substituted furan compounds can be further transformed for the preparation of drug analogs, offering a new route for the high-value utilization of biomass molecules.

With the rapid developments in perovskite solar cell (PSC), high efficiency has been achieved, but the long-term operational stability is still the most important challenges for the commercialization of this emerging photovoltaic technology. So far, bi-dopants Li-TFSI/t-BP doped hole-transporting materials (HTM) have led to state-of-the art efficiency in n-i-p PSCs. However, such dopants have several drawbacks in terms of stability, including the complex oxidation process, undesirable ion migration and ultra-hygroscopic nature. Herein, a fluorine-containing organic Lewis acid dopant bis(pentafluorophenyl)zinc (Zn-FP) with hydrophobic property and high migration barrier has been employed as a potential alternative to widely employed bi-dopants Li-TFSI/t-BP for PTAA. The resulting Zn-FP-based PSCs achieve a maximum PCE of 20.34% with J-V  hysteresis-free. Specifically, the unencapsulated device exhibits significantly advancement of operational stability under the International Summit on Organic Photovoltaic Stability protocols (ISOS-L-1), maintaining over 90% of the original efficiency after operation for 1000 hours under continuous 1-sun equivalent illumination in N2 atmosphere in both forward and reverse J-V scan.

Sustainable battery concepts are of great importance for the energy storage demands of the future. Organic batteries based on redox-active polymers are one class of promising storage systems to meet these demands, in particular when combined with environmentally friendly and safe electrolytes. Deep Eutectic Solvents (DESs) represent a class of electrolytes that can be produced from sustainable sources and exhibit in most cases no or only a small environmental impact. Because of their non-flammability, DESs are safe, while providing an electrochemical stability window almost comparable to established battery electrolytes and much broader than typical aqueous electrolytes. Here, we report the first all-organic battery cell based on a DES electrolyte composed of sodium bis(trifluoromethanesulfonyl)imide (NaTFSI) and N-methylacetamide (NMA) alongside the electrode active materials poly(2,2,6,6-tetramethylpiperidin-1-yl-oxyl methacrylate) (PTMA) and crosslinked poly(vinylbenzylviologen) (X-PVBV2+). The resulting cell shows two voltage plateaus at 1.07 V and 1.58 V and achieves Coulombic efficiencies of 98%. Surprisingly, the X-PVBV/X-PVBV+ redox couple turned out to be much more stable in NaTFSI:NMA 1:6 than the X-PVBV+/X-PVBV2+ couple, leading to asymmetric capacity fading during cycling tests.