Synergistic effects of the substrate-ligand interaction in metal-organic complexes on the de-electronation kinetics of a vitamin C fuel cell.

The rising demand for portable energy conversion devices has spurred the advancement of direct liquid fuel cells (DLFCs) employing fuels such as alcohol, ammonia, hydrazine, and vitamin C. In these devices, various precious metal platforms have been explored to increase the de-electronation kinetics and reduce catalyst poisoning, but with substantial cost implications. We demonstrate the crucial role of ligands in non-precious organometallic complexes in influencing the de-electronation kinetics of fuel molecules through a unique substrate-ligand synergistic interaction.

Ligand Isomerization Driven Electrocatalytic Switching.

The prevailing view about molecular catalysts is that the central metal ion is responsible for the reaction mechanism and selectivity, whereas the ligands mainly affect the reaction kinetics. Here, we question this paradigm and show that ligands have a dramatic influence on the selectivity of the product. We show how even a seemingly small change in ligand isomerization sharply alters the selectivity of the well-researched oxygen reduction reaction (ORR) Co phthalocyanine catalyst from an indirect 2e to a direct 4e pathway.

Aluminium, Nitrogen-Dual-Doped Reduced Graphene Oxide Co-Existing with Cobalt-Encapsulated Graphitic Carbon Nanotube as an Activity Modulated Electrocatalyst for Oxygen Electrocatalyst for Oxygen Electrochemistry Applications.

There is a rising need to create high-performing, affordable electrocatalysts in the new field of oxygen electrochemistry. Here, a cost-effective, activity-modulated electrocatalyst with the capacity to trigger both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) in an alkaline environment is presented. The catalyst (Al, Co/N-rGCNT) is made up of aluminium, nitrogen-dual-doped reduced graphene oxide sheets co-existing with cobalt-encapsulated carbon nanotube units.

Electrochemical energy storage in an organic supercapacitor a non-electrochemical proton charge assembly.

Contrary to conventional beliefs, we show how a functional ligand that does not exhibit any redox activity elevates the charge storage capability of an electric double layer a proton charge assembly. Compared to an unsubstituted ligand, a non-redox active carboxy ligand demonstrated nearly a 4-fold increase in charge storage, impressive capacitive retention even at a rate of 900C, and approximately a 2-fold decrease in leakage currents with an enhancement in energy density up to approximately 70% a non-electrochemical route of proton charge assembly. Generalizability of these findings is presented with various non-redox active functional units that can undergo proton charge assembly in the ligand.

Tailoring COFs: Transforming Nonconducting 2D Layered COF into a Conducting Quasi-3D Architecture via Interlayer Knitting with Polypyrrole.

Improving the electronic conductivity and the structural robustness of covalent organic frameworks (COFs) is paramount. Here, we covalently cross-link a 2D COF with polypyrrole (Ppy) chains to form a quasi-3D COF. The 3D COF shows well-defined reflections in the SAED patterns distinctly indexed to its modeled crystal structure.

Distortion-Induced Interfacial Charge Transfer at Single Cobalt Atom Secured on Ordered Intermetallic Surface Enhances Pure Oxygen Production.

In this work, atomic cobalt (Co) incorporation into the PdGe intermetallic lattice facilitates generation of a thin layer of CoO over Co-substituted PdGe, with Co in the CoO surface layer functioning as single metal sites. Hence the catalyst has been titled Co-CoO-PdGe. High-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy confirm the existence of CoO, with some of the Co bonded to Ge by substitution of Pd sites in the PdGe lattice.

Unprecedented energy storage in metal-organic complexes constitutional isomerism.

The essence of any electrochemical system is engraved in its electrical double layer (EDL), and we report its unprecedented reorganization by the structural isomerism of molecules, with a direct consequence on their energy storage capability. Electrochemical and spectroscopic analyses in combination with computational and modelling studies demonstrate that an attractive field-effect due to the molecule's structural-isomerism, in contrast to a repulsive field-effect, spatially screens the ion-ion coulombic repulsions in the EDL and reconfigures the local density of anions. In a laboratory-level prototype supercapacitor, those with β-structural isomerism exhibit nearly 6-times elevated energy storage compared to the state-of-the-art electrodes, by delivering ∼535 F g at 1 A g while maintaining high performance metrics even at a rate as high as 50 A g.

Unusual Ligand Assistance in Molecular Electrocatalysis via Interfacial Proton Charge Assembly.

We show that the ability of the ligand to reorganize the electric double layer (EDL) often dominates the electrocatalysis contrary to their inductive effect in the spectrochemical series, leading to counterintuitive electrocatalysis. With water oxidation and chlorine evolution as the probe reactions, the same catalytic entity with carboxy functionalized ligand exhibited surprisingly higher electrochemical activity in comparison to the aggressively electron-withdrawing nitro functionalized ligands, which is contrary to their actual location in the spectrochemical series. Spectroscopic and electrochemical analyses suggest the enrichment of catalytically active species in the carboxy substituted ligand via proton charge assembly in the EDL that in turn enhances the kinetics of the overall electrochemical process.

Wurtzite CuGaS with an In-Situ-Formed CuO Layer Photocatalyzes CO Conversion to Ethylene with High Selectivity.

We present surface reconstruction-induced C-C coupling whereby CO is converted into ethylene. The wurtzite phase of CuGaS undergoes in situ surface reconstruction, leading to the formation of a thin CuO layer over the pristine catalyst, which facilitates selective conversion of CO to ethylene (C H ). Upon illumination, the catalyst efficiently converts CO to C H with 75.

Intrinsic Charge Polarization in Bi S Cl Nanorods Promotes Selective CC Coupling Reaction during Photoreduction of CO to Ethanol.

Obtaining multi-carbon products via CO  photoreduction is a major catalytic challenge involving multielectron-mediated CC bond formation. Complex design of multicomponent interfaces that are exploited to achieve this chemical transformation, often leads to untraceable deleterious changes in the interfacial chemical environment affecting CO  conversion efficiency and product selectivity. Alternatively, robust metal centers having asymmetric charge distribution can effectuate CC coupling reaction through the stabilization of intermediates, for desired product selectivity.

Regio-isomerism directed electrocatalysis for energy efficient zinc-air battery.

We have investigated the role of ligand isomerism in modulating the mechanisms and kinetics associated with charge/discharge chemistry of an aqueous metal-air battery. The dominant electron-withdrawing inductive effect (-I effect) and the diminished electron-withdrawing resonance effect (-R effect) in the α-NO isomer noticeably diminishes the rate of oxygen reduction (ORR) and oxygen evolution reactions (OER) on the catalytic Co-center. In their β-counterpart, the cumulative -I and -R effects noticeably enhance the OER and ORR kinetics on the same catalytic Co-center.

La-Cu based heterogeneous perovskite catalyst for highly selective benzene hydroxylation under mild conditions.

Direct hydroxylation of benzene towards phenol with high conversion and selectivity remains a great challenge. We report herein an efficient La CuO perovskite catalyst for one-step oxidation of benzene using hydrogen peroxide under mild conditions. The catalyst was characterized using XRD, TEM, XPS, TG-DTA, and other advanced techniques.

Improvement in Oxygen Evolution Performance of NiFe Layered Double Hydroxide Grown in the Presence of 1T-Rich MoS.

NiFe layered double hydroxide (NiFe LDH) grown in the presence of MoS (rich in 1T phase) shows exceptional performance metrics for alkaline oxygen evolution reaction (OER) in this class of composites. The as-prepared NiFe LDH/MoS composite (abbreviated as MNF) exhibits a low overpotential (η) of 190 mV; a low Tafel slope of 31 mV dec; and more importantly, a high stability in its performance manifested by the delivery of current output for 45 h. It is important to note that this could be achieved with an exceedingly low loading of 0.

Potential- and Time-Dependent Dynamic Nature of an Oxide-Derived PdIn Nanocatalyst during Electrochemical CO Reduction.

Electrochemical reduction of CO into valuable fuels and chemicals is a promising route of replacing fossil fuels by reducing CO emissions and minimizing its adverse effects on the climate. Tremendous efforts have been carried out for designing efficient catalyst materials to selectively produce the desired product in high yield from CO by the electrochemical process. In this work, a strategy is reported to enhance the electrochemical CO reduction reaction (ECORR) by constructing an interface between a metal-based alloy (PdIn) nanoparticle and an oxide (InO), which was synthesized by a facile solution method.

Coordination Flexibility Aided CO -specific Gating in an Iron Isonicotinate MOF.

Coordination flexibility assisted porosity has been introduced into an Iron-isonicotinate metal-organic framework (MOF), (Fe(4-PyC)  ⋅ (OH). The framework showed CO -specific gate opening behavior, which gets tuned as a function of temperature and pressure. The MOF's physisorptive porosity towards CO , CH , and N was investigated; it adsorbed only CO via a gate opening phenomenon.

Lithium silicate nanosheets with excellent capture capacity and kinetics with unprecedented stability for high-temperature CO capture.

An excessive amount of CO is the leading cause of climate change, and hence, its reduction in the Earth's atmosphere is critical to stop further degradation of the environment. Although a large body of work has been carried out for post-combustion low-temperature CO capture, there are very few high temperature pre-combustion CO capture processes. Lithium silicate (LiSiO), one of the best known high-temperature CO capture sorbents, has two main challenges, moderate capture kinetics and poor sorbent stability.

Geometrical Isomerism Directed Electrochemical Sensing.

We report the independent role of isomerism of secondary sphere substituents over their nature, a factor often overlooked in molecular electrocatalysis pertaining to electrochemical sensing, by establishing that isomerism redefines the electronic structure at the catalytic reaction center via geometrical factors. UV-vis spectroscopy and X-ray photoelectron spectroscopy suggest that a substituent's isomerism in molecular catalysts conjoins molecular planarity and catalytic activation through competing field effects and resonance effects. As a classical example, we demonstrate the influence of isomerism of the -NO substituents for the electrocatalytic multi electron oxidation of As(III), a potentially important electrochemical pathway for water remediation and arsenic detection.

Unprecedented Isomerism-Activity Relation in Molecular Electrocatalysis.

The role of electrocatalysts in energy storage/conversion, biomedical and environmental sectors, green chemistry, and much more has generated enormous interest in comprehending their structure-activity relations. While targeting the surface-to-volume ratio, exposing reactive crystal planes and interfacial modifications are time-tested considerations for activating metallic catalysts; it is primarily by substitution in molecular electrocatalysts. This account draws the distinction between a substituent's chemical identity and isomerism, when regioisomerism of the -NO substituent is conferred at the "α" and "β" positions on the macrocycle of cobalt phthalocyanines.

Carbon Derived from Soft Pyrolysis of a Covalent Organic Framework as a Support for Small-Sized RuO Showing Exceptionally Low Overpotential for Oxygen Evolution Reaction.

Electrochemical water splitting is the most energy-efficient technique for producing hydrogen and oxygen, the two valuable gases. However, it is limited by the slow kinetics of the anodic oxygen evolution reaction (OER), which can be improved using catalysts. Covalent organic framework (COF)-derived porous carbon can serve as an excellent catalyst support.

MnO @Fe O Magnetic Nanoparticles as Efficient and Recyclable Heterogeneous Catalyst for Benzylic sp C-H Oxidation.

Herein, we report a highly chemoselective and efficient heterogeneous MnO @Fe O MNP catalyst for the oxidation of benzylic sp C-H group of ethers using TBHP as a green oxidant to afford ester derivatives in high yield under batch/continuous flow module. This catalyst was also effective for the benzylic sp C-H group of methylene derivatives to furnish the ketone in high yield which can be easily integrated into continuous flow condition for scale up. The catalyst is fully characterized by spectroscopic techniques and it was found that 0.

Cu/CuO Nanoparticles Supported on a Phenol-Pyridyl COF as a Heterogeneous Catalyst for the Synthesis of Unsymmetrical Diynes via Glaser-Hay Coupling.

Covalent organic frameworks (COFs) are a new class of porous crystalline polymers with a modular construct that favors functionalization. COF pores can be used to grow nanoparticles (nPs) with dramatic size reduction, stabilize them as dispersions, and provide excellent nP access. Embedding substrate binding sites in COFs can generate host-guest synergy, leading to enhanced catalytic activity.

Direct Z-Scheme g-CN/FeWO Nanocomposite for Enhanced and Selective Photocatalytic CO Reduction under Visible Light.

Photocatalytic reduction of CO to renewable solar fuels is considered to be a promising strategy to simultaneously solve both global warming and energy crises. However, development of a superior photocatalytic system with high product selectivity for CO reduction under solar light is the prime requisite. Herein, a series of nature-inspired Z-scheme g CN/FeWO composites are prepared for higher performance and selective CO reduction to CO as solar fuel under solar light.

Highly Stable COF-Supported Co/Co(OH) Nanoparticles Heterogeneous Catalyst for Reduction of Nitrile/Nitro Compounds under Mild Conditions.

Ordered nanoporosity in covalent organic framework (COF) offers excellent opportunity for property development. Loading nanoparticles (nPs) onto them is one approach to introducing tailor-made properties into a COF. Here, a COF-Co/Co(OH) composite containing about 16 wt% of <6 nm sized Co/Co(OH) nPs is prepared on a N-rich COF support that catalyzes the release of theoretical equivalence of H from readily available, safe, and cheap NaBH .

Gold Incorporated Mesoporous Silica Thin Film Model Surface as a Robust SERS and Catalytically Active Substrate.

Ultra-small gold nanoparticles incorporated in mesoporous silica thin films with accessible pore channels perpendicular to the substrate are prepared by a modified sol-gel method. The simple and easy spin coating technique is applied here to make homogeneous thin films. The surface characterization using FESEM shows crack-free films with a perpendicular pore arrangement.