Cobalt Salts Research Articles

Coordination Compound Derived Co9S8 Supported on Nitrogen and Sulfur Co‐Doped Porous Carbon for Oxygen Reduction Reaction

AbstractCobalt sulfide, a class of metal chalcogenide with tunable electronic structure and component distribution, has attracted considerable interest in renewable energy conversion and utilization. In this work, we report a facile, efficient and scalable method to synthesize Co9S8 supported on nitrogen and sulfur co doped porous carbon (Co9S8/N,S‐PC) hybrid from the annealing treatment of a coordination compound assembled by 2‐mercaptobenzimidazole, 4,4‐bipyridine and cobalt salt. The heteroatom of organic ligand could efficiently tune the electronic properties of Co9S8 nanoparticles and well‐designed carbon. Meanwhile the interaction of organic ligands provides a platform for the high dispersion of Co9S8. Owing to the synergetic effect, the Co9S8/N,S‐PC catalyst shows an admirable oxygen reduction reaction (ORR) activity with the E1/2 of 0.804 V vs. RHE, together with good durability, and tolerance to methanol poisoning in alkaline media.

Synthesis and properties of graphene-like porous carbon from modified cellulose

The work is devoted to the synthesis of graphene-like magnetic nanocomposites by direct pyrolysis of hemp microcrystalline cellulose modified with citric acid containing nickel or cobalt salts. Their chemical structure and morphology were characterized by X-ray diffraction (XRD), electron microscopy (SEM), Raman spectroscopy, low-temperature N2 adsorption-desorption, and Fourier transform infrared spectroscopy (FT-IR). Thermogravimetry has established a possible mechanism of pyrolysis of a modified cellulose matrix containing Ni and Co metals. X-ray diffraction analysis and Raman spectroscopy have shown that an increase in the number of carboxyl groups accelerates the process of graphitization of the cellulose matrix with transition metals (Ni and Co), as well as increases the degree of structural order and the level of graphitization. The conducted studies have shown that nanoparticles of metals of the zero-valence state are enclosed in graphene-like shells having a mainly mesoporous structure.

Constructing multi-path channels in graphene oxide-based membrane for high-efficiency oil/water separation

Graphene oxide (GO) membranes have demonstrated significant potential for effective wastewater treatment; however, their tortuous and irregular water transport pathways through stacked nanosheets pose considerable challenges. In this study, we present a novel approach for fabricating faveolate-structured graphene oxide nanomesh (GONM) membranes, enhanced by the in situ growth of Co(OH)2 nanosheets to facilitate oil–water separation. The incorporation of in-plane pathways through the porous GONM, alongside the enlargement of interlayer pathways from Co(OH)2 growth, significantly improves water permeance. The nanopores present in the holey GONM reduce diffusion pathways, while intercalation of Co(OH)2 nanosheets increases channel sizes and stabilizes the GONM structure. By manipulating the mass ratio between GONM and cobalt salt, we optimized the membrane, achieving an exceptional water permeance of 224.2 L m-2h−1 bar−1, surpassing GO membranes. Additionally, the resultant membranes exhibit remarkable underwater anti-oil adhesion performance and efficient separation capabilities for a wide variety of oil-in-water emulsions, with separation efficiencies exceeding 99.1 %. This work provides valuable insights into the intentional manipulation of surface topography and hierarchical nanochannels in membrane materials, paving the way for high-efficiency water treatment solutions.

Cobalt-catalysed desymmetrization of malononitriles via enantioselective borohydride reduction.

The high nitrogen content and diverse reactivity of malononitrile are widely harnessed to access nitrogen-rich fine chemicals. Although the facile substitutions of malononitrile can give structurally diverse quaternary carbons, their access to enantioenriched molecules, particularly chiral amines that are prevalent in bioactive compounds, remains rare. Here we report a cobalt-catalysed desymmetric reduction of disubstituted malononitriles to give highly functionalized β-quaternary amines. The pair of cobalt salt and sodium borohydride is proposed to generate a cobalt-hydride intermediate and initiate the reduction. Meanwhile, the enantiocontrol of the dinitrile is achieved through a tailored bisoxazoline ligand with two large flanks that create a narrow gap to host the bystanding nitrile and thus restrict the C(ipso)-C(α) bond rotation of the complexed one. Combined with the extensive derivatization possibilities of all substituents on the quaternary carbon, this asymmetric reduction unlocks pathways from malononitrile as a bulk chemical feedstock to intricate, chiral nitrogen-containing molecules.

Poly (lactic acid)/Poly (butylene adipate-co-terephthalate) Films with Simultaneous High Oxygen Barrier and Fast Degradation Properties

Although poly (lactic acid) (PLA) is a good environmentally-friendly bio-degradable polymer which is used to substitute traditional petrochemical-based polymer packaging films, the barrier properties of PLA films are still insufficient for high-barrier packaging applications. In this study, oxygen scavenger hydroxyl-terminated polybutadiene (HTPB) and cobalt salt catalyst were incorporated into the PLA/poly (butylene adipate-co-terephthalate) (PLA/PBAT), followed by melting extrusion and three-layer co-extrusion blown film process to prepare the composite films. The oxygen permeability coefficient of the composite film combined with 6 wt% oxygen scavenger and 0.4 wt% catalyst was decreased significantly from 377.00 cc∙mil∙m-2∙day-1∙0.1MPa-1 to 0.98 cc∙mil∙m-2∙day-1∙0.1MPa-1, showing a remarkable enhancement of 384.69 times compared with the PLA/PBAT composite film. Meanwhile, the degradation behavior of the composite film was also accelerated, exhibiting a mass loss of nearly 60% of the original mass after seven days of degradation in an alkaline environment, whereas PLA/PBAT composite film only showed a mass loss of 32%. This work has successfully prepared PLA/PBAT composite films with simultaneously improved oxygen barrier property and degradation behavior, which has great potential for high-demanding green chemistry packaging industries, including food, agricultural, and military packaging.

Eco-friendly synthesis of nano ferrites for effective dye degradation and enhanced antimicrobial protection

This study investigates the synthesis of cobalt and nickel ferrite NPs using Araucaria heterophylla resin as a bio- template and nitrate salts of cobalt, nickel, and iron as precursors.The resulting spinel systems exhibit efficient degradation of organic dyes, including methylene blue and rhodamine-B, and demonstrate excellent reusability. The NPs antibacterial efficacy against pathogenic bacteria, such as Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Salmonella paratyphi, was also evaluated. Comprehensive characterization of the nanomaterials was performed using FT-IR, XRD, SEM, TEM, EDX, and VSM techniques. Magnetic measurements revealed the ferromagnetic nature of cobalt ferrites and the superparamagnetic nature of nickel ferrites, with reduced saturation magnetization and coercivity compared to bulk materials due to the quantum size effect. The nano-formulated ferrites exhibited superior antibacterial activity, highlighting their potential for water treatment applications. This study underscores the importance of removing dye contaminants from wastewater before discharge into aquatic ecosystems.

Synergistic effects of MXene support and cobalt salts in dye-sensitized photocatalytic hydrogen generation

This study introduces an approach to photocatalytic hydrogen production through a dye-sensitized photocatalytic system employing MXene (Ti3C2Tx) and a non-noble cobalt metal catalyst. It was demonstrated that simple integration of eosin Y, Ti3C2Tx and cobalt salt (CoSO4) significantly enhances the photocatalytic hydrogen evolution, outperforming the corresponding system that does not include Ti3C2Tx. The key to this enhanced performance lies in the unique properties of MXene material, which facilitates effective electron transfer and acts as a support for dye and catalyst. The successful well-dispersed decoration of small (2–3 nm) cobalt-based nanoparticles on the Ti3C2Tx sheet via in situ photodeposition was confirmed by transmission electron microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). The optimal hydrogen production rates were achieved with a Co to Ti3C2Tx mass ratio of 15%. This optimized interaction results in a hydrogen evolution rate of 40.1 mmol h−1 g−1 and an apparent quantum efficiency (AQE) of 35.4% at 505 nm. These findings highlight the potential of Ti3C2Tx as a versatile component in photocatalytic systems, particularly effective when paired with economically viable, earth-abundant catalysts like cobalt.

Cobalt/nitrogen co-doped carbon nanosheets from coal-based graphene quantum dots boosted oxygen reduction

We report on cobalt/nitrogen co-doped carbon nanosheets (Co/NCNs) as a highly efficient electrocatalyst for the oxygen reduction reaction (ORR). The Co/NCNs were synthesized through pyrolysis at 900 °C using coal-based graphene quantum dots that contain nitrogen as a source of both carbon and nitrogen, NaCl as a template, and trace amounts of cobalt salt as a metal source. The Co/NCNs-0.1 exhibited ORR activity that was equivalent to that of Pt/C, with a half-wave potential of 0.85 V and a limiting current density of 4.9 mA cm−2. Furthermore, the zinc-air battery incorporating Co/NCNs-0.1 demonstrated an open circuit voltage of 1.423 V, a maximum power density of 149 mW cm−2, and a specific capacity of 806.5 mAh g−1 at a current density of 20 mA cm−2. The results of density functional theory calculations indicate that metal Co, when protected by graphitic-N-doped carbon, holds a greater negative charge and exhibits a lower energy barrier compared to other types of nitrogen species. This property contributes to the catalytic activity of the ORR.

Understanding different oxidation methods for the hole transport layer Spiro-OMeTAD to improve perovskite solar cell performance

The preparation of a high-performance hole transport layer is a pivotal factor in achieving efficiency and stable perovskite solar cells. 2,2’,7,7’-Tetrakis[N, N-di(4-methoxyphenyl)amino]−9,9’-spirobifluorene (Spiro-OMeTAD) currently stands as the most widely employed hole transport material in high-performance perovskite solar cells. The current methodologies for its preparation primarily revolve around three techniques: O2 oxidation, cobalt salt doping, and CO2 bubbled doping. In this study, we systematically investigated and analyzed Spiro-OMeTAD prepared through these three methods, from solution and film to device. The CO2-bubbled method and Co-doped method allow for faster and more complete oxidation of Spiro-OMeTAD while maintaining conductivity and energy level matching. Therefore, the film of both methods shows better carrier extract capabilities and defect states than that of O2-oxidized. In particular, the film of the CO2-bubbled method had better hydrophobicity and thermal stability, showing the least degradation at 85 °C annealing, which can be attributed to the removal of hydrophilic Li+. This study could inspire further optimization of Spiro-OMeTAD film fabrication processes in perovskite solar cells.

Two new 3D cobalt(II) coordination polymers constructed by semi-rigid carboxylic acid ligand: Syntheses, structures and properties

Two novel coordination polymers, {[Co2(L)(H2O)5]·H2O}n (1), and {[Co5(L)2(H2O)6(μ3-OH)2]·2C3H7NO·2H2O}n (2) (H4L = 3, 3′, 5, 5′-diphenyl ether tetracarboxylic acid, C16H10O9) have been synthesized by assembling semi-rigid aromatic polycarboxylic acids with transition-metal cobalt salts, and structurally characterized by elemental analysis, thermogravimetric analysis, IR spectrum, powder X-ray diffraction, and single crystal X-ray diffraction analysis. Structural analysis showed both the L ligands in CP 1 and CP 2 were regarded as 4 connection points, while the binuclear clusters in CP 1 and the pentanuclear clusters in CP 2 were regarded as 4 connection points and 8 connection points, respectively. Finally, both CP 1 and CP 2 were 3D network structures connected by two nodes (4, 4-connected for CP 1 and 4, 8-connected for CP 2). In addition, temperature-dependent susceptibilities have been measured in the range of 2 to 300 K, indicating that both CP 1 and CP 2 have antiferromagnetic coupling between adjacent Co(II) ions. Finally, Electrochemical experiments show that the CP 1 and CP 2 have good electrochemical behaviors.

Investigating solvent effects on synthesizing novel cobalt hydroxide and fluoride complex from Co(BF4)2 as active materials of the battery supercapacitor hybrid

Metal-organic framework (MOF) derivatives with tunable pore structure and improved conductivity are intensively designed as electroactive materials. Incorporating structure directing agents (SDA) is beneficial for designing MOF derivatives with excellent electrochemical performances. Ammonium fluoroborate has been reported as an effective SDA, coupled with cobalt salt and 2-methylimidazole, to synthesize zeolitic imidazolate framework-67 (ZIF-67) derivatives for charge storage. However, the synthetic environment for growing cobalt-based active materials is relatively complex. In this study, cobalt tetrafluoroborate (Co(BF4)2) is proposed as a novel cobalt precursor, supplementing cobalt ions and acting as the SDA in a single chemical, to synthesize the cobalt-based electroactive material of energy storage electrodes. Interactions between solvent molecules and solutes play significant roles on the morphology, composition, and electrochemical performance of active materials. Deionized water, methanol and ethanol are used as precursor solvents to understand their effects on material and electrochemical properties. The optimal electrode presents a specific capacitance of 608.3 F/g at 20 mV/s, attributed to the highest electrochemical surface area and evident compositions of cobalt fluoride and hydroxide. A battery supercapacitor hybrid achieves the maximum energy density of 45 Wh/kg at 429 W/kg. The CF retention of 100% and Coulombic efficiency of 99% are achieved after 10,000 cycles.

Synthesis, structural, biological applications, DFT, molecular docking studies on Fe(III), Co(II), and Ni(II) complexes incorporating 2‐(pyridin‐2‐yl)phenol and 1H‐benzimidazole‐2‐carboxylic acid

This study provides a detailed investigation into the synthesis, characterization, and biological activities of the coordination compounds FePPHBZC, CoPPHBZC, and NiPPHBZC. These compounds were synthesized with high yields by reacting chloride salts of Iron, Cobalt, or Nickel with 2‐(pyridin‐2‐yl)phenol (PPH) and 1H‐benzimidazole‐2‐carboxylic acid (BZC) in a 1:1:1 ratio. Various techniques including spectroscopic (IR, UV–vis, mass spectra), elemental analysis, conductivity, magnetic, and thermal analyses confirmed the formation and structure of these coordination compounds. Density functional theory (DFT) calculations were used to study their electronic structure, stability, and reactivity. 3D modeling revealed hexacoordinated geometries for Fe and Co complexes and a tetrahedral coordination for the Ni complex. Analysis of the highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), and other reactivity parameters indicated changes in reactivity upon metal coordination. Molecular Electrostatic Potential (MEP) diagrams identified electron‐rich areas prone to nucleophilic attack, important for protein interactions during docking studies. Biological evaluations demonstrated that metal–ligand complexes exhibit enhanced antimicrobial, antioxidant, and anti‐inflammatory activities compared to individual ligands, with larger inhibition zones and higher inhibitory activity. Molecular docking studies showed strong interactions between metal–ligand complexes and target proteins, suggesting potential therapeutic applications. Among them, FePPHBZC exhibited the strongest interactions, followed by CoPPHBZC and NiPPHBZC, characterized by hydrogen bonding, ionic interactions, and other non‐covalent interactions, contributing to their enhanced stability and binding affinity.

Cobalt(II) Catalyzed Proficient Synthesis of Enaminones from Aryl-Alkenes and Amines

A simple, cost-effective and modular strategy has been developed to synthesize synthetically and pharmaceutically active enaminones via oxidative amination of aryl alkenes with amines and CHCl3 using tert-butylhydrogen peroxide (TBHP) as an oxidant. Herein, we describe the synthesis of enaminones from vinyl arenes and sterically hindered diisopropylethylamine (DIPEA) by employing earth-abundant cobalt salt as a catalyst within very short reaction time for the first time. Furthermore, nitrogen and oxygen containing heterocyclic compounds have been synthesized from these highly functionalized enaminones. Moreover, various controlled experiments such as radical trapping reaction along with Hammett analysis with various type of substituents on the styrene ring unravel the detailed mechanism of this reaction pathway.

Characterization of the hypergolic ignition of green fuels with hydrogen peroxide by drop test and jet impingement

This work presents an experimental study on the hypergolic behavior of variants of N,N,N’,N’-tetramethylethylenediamine (TMEDA)/N,N-dimethylethanolamine (DMEA) system, named PAHyp 0, with 93 wt% hydrogen peroxide. Two different copper-based catalyst and one cobalt-based catalytic agent were dissolved in the fuels to trigger the pre-ignition reactions. When employing copper chloride dihydrate, the resultant fuel requires methanol (ternary system) as a stabilizing agent, whereas both carboxylic salts of copper and cobalt dissolved in TMEDA/DMEA deliver a stable formulation (binary system) without the need for any organic solvent. Shadowgraph high-speed imaging was used to capture the ignition process and pressure wave development of over 30 fuel samples in a modified drop test. An ignition/stability envelope was proposed to map the safe and unstable formulations. It was demonstrated that the concentration of TMEDA should be no more than 50% in the binary system, while the amount of methanol should fall within a concentration window of 33 to 50% in the ternary system. Lower loadings of catalyst, ranging from 0.5 to 1.0 wt%, are required to deliver stable fast-igniting fuels. Three promising formulations catalyzed with 1 wt% copper salts were selected to perform impinging jet fire experiments. Impinging jets yielded significantly lower ignition delay times than drop tests due to the better mixing conditions. However, it was verified that ignition may fail for low values of jet velocities, below 0.8 m/s, and for high jet velocities, exceeding 14 m/s. An attempt to explain the ignition and non-ignition events was made by using the fundamentals of explosion limits of the hydrogen/oxygen system and oxidation reactions at low temperature. Remarkably, ultra-fast ignitions of about 10 ms were measured by the impinging jet setup within near-optimal operational conditions. Therefore, TMEDA/DMEA-based fuels with reduced catalyst loadings (0.5–1.0 wt%) offer new opportunities in aerospace propulsion and should be further studied.

Cobalt-Imidazole Complexes: Effect of Anion Nature on Thermochemical Properties.

A solvent-free method was proposed for the synthesis of hexaimidazolecobalt(II) nitrate and perchlorate complexes-[Co(C3H4N2)6](NO3)2 and [Co(C3H4N2)6](ClO4)2-by adding cobalt salts to melted imidazole. The composition, charge state of the metal, and the structure of the resulting complexes were confirmed by elemental analysis, XPS, IR spectroscopy, and XRD. The study of the thermochemical properties of the synthesized complexes showed that [Co(C3H4N2)6](NO3)2 and [Co(C3H4N2)6](ClO4)2 are thermally stable up to 150 and 170 °C, respectively. When the critical temperature of thermal decomposition is reached, oxidative two-stage gasification is observed. In this case, the organic component of the [Co(C3H4N2)6](NO3)2 complex undergoes almost complete gasification to form Co3O4 with a slight admixture of CoO, which makes it attractive as a component of gas-generation compositions, like airbags.

Exploring the molecular structure and in vitro biological potential of newly synthesized Fe(III), Co(II), and Ni(II) coordination compounds with 2-(pyridin-2-yl)-1H-benzimidazole and phenylalanine ligands

This study presents a thorough investigation into the synthesis, characterization, computational analysis, and biological evaluation of FePBZPHA, CoPBZPHA, and NiPBZPHA mixed-ligand complexes. They were synthesized in high yields via reactions between chloride salts of Iron, Cobalt, or Nickel with 2-(pyridin-2-yl)-1H-benzimidazole (PBZ) and Phenylalanine (PHA). They underwent extensive spectroscopic, elemental, conductivity, magnetic, and thermal analysis to confirm their formation. Molar conductivity measurements indicated their non-electrolytic nature, with UV–vis spectra revealing distinct absorption bands for PBZ and PHA ligands, shifting significantly upon metal ion coordination. Stoichiometry determination confirmed the 1:1:1 (M:PBZ:PHA) ratio, while FT-IR spectra comparison elucidated intricate binding modes, supported by mass spectra and elemental analysis. Thermal analysis revealed their thermal stability and decomposition pathways. DFT calculations unveiled octahedral coordination geometries and enhanced electron affinity, electronegativity, and reactivity of metal complexes. Biological evaluation showcased significantly enhanced efficacy of metal complexes in antimicrobial, anti-inflammatory, and antioxidant activities, with FePBZPHA exhibiting the highest potency. Molecular docking analysis highlighted their potential as therapeutic agents, with metal complexation enhancing binding affinity and interaction versatility. Overall, this study provides comprehensive insights into the synthesis, characterization, computational analysis, and biological evaluation of FePBZPHA, CoPBZPHA, and NiPBZPHA mixed-ligand complexes, suggesting promising applications in biomedicine and materials science.

Interfacial engineering layered bimetallic oxyhydroxides for efficient oxygen evolution reaction

Transition metal-based oxyhydroxides (MOOH) have garnered significant attention as promising catalyst for the Oxygen Evolution Reaction (OER). However, the direct synthesis of MOOH poses challenges due to the instability of trivalent cobalt and nickel salts, attrivuted to their high oxidation states. In this study, theoretical computations predicted that Co(OH)2 nanosheets are exclusively formed on carbon structures, owing to the stronger binding energy between CoOOH and CC compared to Co(OH)2. Furthermore, the presence of FeOOH interface reduces the binding energy between CoOOH and carbon structure. Experiment evidence confirms that CoOOH can be directly synthesized through controlled epitaxial growth on an FeOOH interface using a hydrothermal method. Moreover, the in-situ doping of iron leads to the formation of high-quality Fe0.35Co0.65OOH with exceptional OER performance, displaying a low overpotential of 240 mV at 10 mA cm−2 and a small Tafel slope of 43 mV dec-1. Density functional theory (DFT) calculations uncover the substantial enhancement of oxygen-containing species adsorption abilities by Fe0.35Co0.65OOH, resulting in improved OER activity. This work presents a promising strategy for the efficient preparation of layered cobalt oxyhydroxides, enabling efficient energy conversion and storage.

Synthesis and polyester printing applications of transition metal complexes of tridentate 5-(m-tolyldiazenyl)salicylaldehyde thiosemicarbazone derivatives

Thiosemicarbazone metal complexes are intriguing molecules with a variety of applications in several fields, including the pharmaceutical sector, analytical chemistry, and textile industries. Here, we designed and synthesized 12 transition metal complexes based on thiosemicarbazone as a tridendate group and azo moiety as a chromophore part, in addition to evaluating their color strength and fastness properties. The tridentate ligand derivatives of 5-(m-tolyldiazenyl)salicylaldehyde thiosemicarbazone reacted with four transition metal salts (copper, cobalt, nickel, and iron salts) in refluxing alkaline ethanol to afford the corresponding thiosemicarbazone complexes. The ligands behaved as double-deprotonated tridentate ligands that connected to the transition metal ions through the deprotonation of phenolic-OH and thiol-SH, as well as the azomethine nitrogen atom, to generate fused five- and six-membered heterocycle rings. The obtained metal complexes were characterized by elemental analyses, atomic absorption, IR, and UV–Vis spectra. The color strength and fastness properties of the printed fabrics were tested, showing good to excellent properties.

A nanochanneled silver-deficient oxalatocobaltate(III) complex anion with hydronium as counter cation: Synthesis, crystal structure, thermal analysis and magnetism

A novel cobalt(III) salt, (H3O)0.6[Ag2.4Co(C2O4)3]·6H2O (1), a member of the rare paramagnetic CoIII-open framework materials, has been synthesized in water and characterized by standard methods, including elemental and thermal analyses, IR, UV-Vis and EDX spectroscopies, and single-crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic I2/a space group. In the crystal structure, the Co(III) centers are pseudo-octahedrally chelated by three oxalato ligands with usual propeller orientation. The structure can be best described as an anionic silver-deficient oxalatocobaltate(III) [Ag2.4Co(C2O4)3]0.6- framework with isolated nanochannels parallel to the a axis, hosting highly disordered water molecules carrying protons (hydronium ions). Thermal analysis showed significant weight losses corresponding to the elimination of crystal water molecules followed by the decomposition of the network. Temperature-dependence susceptibility measurements investigated in the temperature range 2–300 K revealed antiferromagnetic ordering at low temperatures (T ≤ 25 K), the Curie–Weiss constants being C = 1.60 emu Oe−1 K and θ = -50 K.

Experimental optimization of the sono-photocatalytic hydrogen evolution reaction (HER) using 1D ZnO and cobalt phthalocyanine

This study presents the sono-photocatalytic hydrogen generation (HER), using ZnO and theraphthal, a water-soluble sodium salt of cobalt 4,5-carboxyphthalocyanine (TP). HER efficiency was optimized by a multivariable design of experiments modifying 5 factors (additives): (i) ascorbic acid, (ii) zinc oxide load, (iii) ultrasound power, (iv) ethanol, and (v) theraphthal under UV irradiation. Differences in hydrogen production according to the variable employed factors were observed in the reactions, resulting in higher yields when larger amounts of ethanol were used. Hydrogen evolution reached a maximum concentration near to 67 μmol (669 μmol g−1) in the HER process, when zinc oxide, theraphthal, and ascorbic acid in water/ethanol mixture were combined. Statistical analysis suggests that the H2 production was influenced mainly by the presence of alcohol in the reaction medium.