Electroanalytical Behavior Research Articles

Voltammetric Investigation of Paracetamol Detection in Acidic Conditions by Using Cork-Modified Carbon Paste Electrodes

Developing new products that satisfy performance and durability expectations while also addressing environmental concerns is possible through the reuse of residues produced by industrial processes, aiming to fulfill the principles of circular economy. In this study, we improved the performance of a carbon paste sensor by incorporating untreated (RC) and regranulated/thermally treated (RGC) cork, which are considered biomass residues from the cork industry. We explored the electroanalytical behavior of paracetamol in sulfuric acid solutions using cyclic voltammetry and differential pulse techniques. The cork-modified carbon paste sensors showed greater sensitivity towards paracetamol. Both modified sensors allowed for an excellent resolution in distinguishing the voltammetric responses of paracetamol in sulfuric acid, showing for both an increase in peak currents compared to the unmodified carbon paste electrode. The quantification of paracetamol without interference has proved to be a feasible operation for the RC- and RGC-modified carbon paste sensors; notably, the first showed the most favorable limits of detection (LD = 2.4112 µM) and quantification (LQ = 8.0373 µM) for paracetamol in the sulfuric acid solution, performing significantly better than the second (LD = 10.355 µM, and LQ = 34.518 µM). Finally, the practical utility of the proposed sensors was assessed by analyzing paracetamol in pharmaceutical samples, obtaining satisfactory results that were in line with those obtainable using high-performance liquid chromatography.

Determination of Sodium Ion Diffusion Coefficient in Tin Sulfide@Carbon Anode Material Using GITT and EIS Techniques

The electroanalytical behavior of SnSx (x = 1, 2) encapsulated into a carbon phase was studied using the galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS). These techniques are widely utilized in battery systems to investigate the diffusion of alkali metal cations in anode and cathode materials depending on the concentration of ions in the host material. Here, we report different calculation methods showing how the applied model affects the derived diffusion coefficient. The calculated value of the apparent chemical diffusion coefficient of sodium ions (DNa+) is in the range of 1 × 10−10 to 1 × 10−15 cm2/s depending on the technique, mathematical protocol, geometry of the electrode material, and applied potential.

Characterization of an In-Situ Soil Organic Carbon (SOC) via a Smart-Electrochemical Sensing Approach.

Soil is a vital component of the ecosystem that drives the holistic homeostasis of the environment. Directly, soil quality and health by means of sufficient levels of soil nutrients are required for sustainable agricultural practices for ideal crop yield. Among these groups of nutrients, soil carbon is a factor which has a dominating effect on greenhouse carbon phenomena and thereby the climate change rate and its influence on the planet. It influences the fertility of soil and other conditions like enriched nutrient cycling and water retention that forms the basis for modern 'regenerative agriculture'. Implementation of soil sensors would be fundamentally beneficial to characterize the soil parameters in a local as well as global environmental impact standpoint, and electrochemistry as a transduction mode is very apt due to its feasibility and ease of applicability. Organic Matter present in soil (SOM) changes the electroanalytical behavior of moieties present that are carbon-derived. Hence, an electrochemical-based 'bottom-up' approach is evaluated in this study to track soil organic carbon (SOC). As part of this setup, soil as a solid-phase electrolyte as in a standard electrochemical cell and electrode probes functionalized with correlated ionic species on top of the metalized electrodes are utilized. The surficial interface is biased using a square pulsed charge, thereby studying the effect of the polar current as a function of the SOC profile. The sensor formulation composite used is such that materials have higher capacity to interact with organic carbon pools in soil. The proposed sensor platform is then compared against the standard combustion method for SOC analysis and its merit is evaluated as a potential in situ, on-demand electrochemical soil analysis platform.

Multiscale modeling of Na2WO4–WO3–CoO melt diffusion layer for molecular dynamics combined with finite element analysis

In the process of molten salt electrolysis of spent tungsten carbide for the separation of tungsten and cobalt, the nature of the molten salt has a crucial impact on product quality and efficiency. In this study, the microscopic and macroscopic models of the diffusion layer of Na2WO4–WO3–CoO molten salt were developed. The structure, transport properties and electroanalytical behavior of Na2WO4–WO3–CoO molten salt were investigated by combining molecular dynamics and finite element simulation under different CoO and WO3 molar ratios and different applied electric field conditions. The cost of this approach is relatively low compared to experiments. It was found that the addition of CoO hinders the mass transfer and increases the electrochemical impedance. The reason for this is that the addition of CoO leads to an increase in the entropy of the molten salt. The change in external electric field does not affect this law. The calculated results are in general agreement with the available experimental data. In the study of the structure of molten salts, the vacancy volume factor, which is a metric for evaluating the size of the vacancy volume of molten salts, was proposed for the first time. The addition of CoO also affects the microstructure, which can be used to infer changes in the electrodeposition products. Experimental results of electrodeposition support this speculation. This study confirms that a combination of macroscopic and microscopic, molecular dynamics and finite element simulations can theoretically aid the development of molten salt electrolysis processes.

Electrochemical Study of 17β-Estradiol and its Determination in Pharmaceutical Preparations using Square Wave Voltammetry

In the present study, the electroanalytical behavior of 17β-estradiol was investigated using cyclic voltammetry. The procedure was based on 17β-estradiol being electrochemically oxidized at a platinum electrode in non-aqueous solutions. At 1.47 V, the oxidation peak was noted. It was discovered that 17β-estradiol's oxidation was diffusion-controlled. Additionally, a quick and easy square wave voltammetry method was developed and validated in this work to determine 17β-estradiol in pharmaceutical preparations. The calibration curve was linear at 5 and 30 µg/mL concentrations. The precision was given by relative standard deviation and was less than 3.36%. Accuracy was given with relative error and did not exceed 2.54%. In pharmaceutical preparations, 17β-estradiol had an average recovery of 100.3%. Under the chosen experimental conditions, no interference was found. The suggested method is highly accurate and precise. Therefore, the method applies to measuring 17β-estradiol in pharmaceutical formulations.

Co-CoO-Co3O4 Realizes ultra highly sensitive detection of 4-nitrochlorobenzene based on synergistic effect of adsorption and catalysis

Accurate determination of 4-nitrochlorobenzene (4-NCB) concentrations in water environment always keeps its challenge due to the high toxicity and redox inertness of organic pollutants. Herein, cobalt-based oxide nanomaterials with different oxidation states were prepared by annealing ZIF-67 under N2 protection and subsequent oxidation in air. The products obtained from non-oxidation, oxidation for 4 and 8 h were named Co, Co-CoO-Co3O4 and Co3O4, respectively. Compared with Co and Co3O4, incompletely oxidized Co-CoO-Co3O4 exhibited the best detection performance for the electroanalytical behavior of 4-NCB, with a high sensitivity of 2.29 μA μM−1 in the concentration range of 0.5–4 μM. The results show that the Co-CoO-Co3O4 composite obtained by Co oxidation for 4 h has a slight decrease in the adsorption capacity of 4-NCB, but its catalytic reduction performance is improved by about 4 times, and the improvement of catalytic ability makes it have more excellent electrochemical detection performance. It is confirmed that the synergistic effect of adsorption and catalysis affects the electrochemical detection performance of organic pollutants, and the catalytic behavior of the material is a more critical factor affecting electrochemical detection.

Copper nanostructures anchored on renewable carbon as electrochemical platform for the detection of dopamine, fluoxetine and escitalopram

For the first time, renewable carbon (RC) from bamboo-biomass modified with copper nanoparticles (CuNPs) has been prepared via a chemical reduction step for the electroanalytical detection of dopamine (DOP), fluoxetine (FXT) and escitalopram (EST). The synthesized RCCuNPs nanocomposite morphology and structural composition were characterized by FEG-SEM along with EDS analysis. The electroanalytical behavior of the target analytes was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The analytical range of detection of DOP, FXT, and EST was 0.05–5.0, 0.1–10, and 0.02–5.0 µmol L−1, respectively. The limits of detection (LOD) were found to be 0.04, 0.05, and 0.25 µmol L−1, respectively. In addition, the standard addition method was used for the detection and recovery of DOP in synthetic human urine and EST in tap water samples. The synergistic effect of CuNPs coupled with the highly porous RC material provided a sensitive, low-cost, and easy to prepare sensing platform for detecting target analytes in clinical and environmental samples.

MXene nanoflakes decorating ZnO tetrapods for enhanced performance of skin-attachable stretchable enzymatic electrochemical glucose sensor

Continuous painless glucose monitoring is the greatest desire of more than 422 million diabetics worldwide. Therefore, new non-invasive and convenient approaches to glucose monitoring are more in demand than other tests for microanalytical diagnostic tools. Besides, blood glucose detection can be replaced by continuous glucose monitoring of other human biological fluids (e.g. sweat) collected non-invasively. In this study, a skin-attachable and stretchable electrochemical enzymatic sensor based on ZnO tetrapods (TPs) and a new class of 2D materials - transition metal carbides, known as MXene, was developed and their electroanalytical behavior was tailored for continuous detection glucose in sweat. The high specific area of ZnO TPs and superior electrical conductivity of MXene (Ti3C2Tx) nanoflakes enabled to produce enzymatic electrochemical glucose biosensor with enhanced sensitivity in sweat sample (29 μA mM−1 cm−2), low limit of detection (LOD ≈ 17 μM), broad linear detection range (LDR = 0.05–0.7 mM) that satisfices glucose detection application in human sweat, and advanced mechanical stability (up to 30% stretching) of the template. The developed skin-attachable stretchable electrochemical electrodes allowed to monitor the level of glucose in sweat while sugar uptake and during physical activity. Continuous in vivo monitoring of glucose in sweat obtained during 60 min correlated well with data collected by a conventional amperometric blood glucometer in vitro mode. Our findings demonstrate the high potential of developed ZnO/MXene skin-attachable stretchable sensors for biomedical applications on a daily basis.

Sonochemical-assisted synthesis of zinc vanadate microstructure for electrochemical determination of metronidazole

In this work, zinc vanadate microstructure (Zn3(VO4)2, ZnV MS) was successfully synthesized via the sonochemical method for the determination of metronidazole (MTZ). The crystalline structure, surface morphology, and chemical composition of the prepared ZnV MS were characterized by analytical techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS) analyses. The electro-kinetic properties of ZnV MS were tested using both anodic and cathodic redox couple. Furthermore, their electroanalytical behavior was successfully investigated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. The ZnV MS displayed excellent electrocatalytic performance in the presence of MTZ than that of an unmodified electrode. Under the optimized conditions, the ZnV MS-fabricated electrode demonstrated a broad linear range from 0.05 to 1303 µM with the low detection limit of 0.009 µM (S/N = 3) and an obtained sensitivity of 0.445 µA µM–1 cm–2. Additionally, the proposed electrode was successfully applied in the detection of MTZ in milk samples with a recovery range of 92–98%.

Electrochemical determination of novel psychoactive substances by differential pulse voltammetry using a microcell for boron-doped diamond electrode and screen-printed electrodes based on carbon and platinum

25B-NBOMe, benzylpiperazine (BZP), 1-(3-chlorophenyl)piperazine (mCPP), and N,N-dimethyltryptamine (DMT) are potent hallucinogenic and stimulant drugs which have emerged as novel psychoactive substances (NPS). The electroanalytical behavior of these compounds was investigated by differential pulse voltammetry (DPV) on boron-doped diamond (BDD) electrode assembled in a homemade microcell, and disposable screen-printed electrodes based on bare carbon (SP-C) and platinum (SP-Pt). The low-cost micro-method proposed in this paper requires volume ranging from 50 μL to 100 μL, minimal sample preparation, and generates very few residues. The electrochemical screening exhibited anodic peaks studied by linear regression of five-point analytical curves (n = 3) which allowed for estimating the sensitivity, limits of detection (LOD) and quantification (LOQ), repeatability (Sr), and intermediate precision (SRW). These results translate into methods with high sensitivity, satisfactory precision (range of 1.7% to 9.0%) and low limits of detection (LOD from 0.15 μg/mL to 1.8 μg/mL) with analytical value in clinical and forensic techniques. Accuracy and applicability of the voltammetric method was assessed in spiked oral fluid samples by standard additions calibration curves with recovery ranging from 98% to 103%. For the first time, the electrochemical data obtained by DPV on three different working electrodes and the analytical parameters are compared for these NPS.

Electroanalytical Investigation of Nimesulide by Differential Pulse Polarography: Method Validation

Nimesulide is a new non-steroidal anti-inflammatory analgesic drug. In the last eight decades, voltammetric methods has become a popular tool for the study of electrochemical reactions. the electroanalytical behavior of nimesulide using differential pulse polarography techniques. Using this technique, the effect of increasing concentration of nimesulide, scan rate and repetitive scanning on the peak height (Ip) and peak potential (Ep) of each compound will be investigated. The general procedure can be used to obtain DPP Polarogram of nimesulide. A study was carried out using optimum parameters to observe a relationship between Ip and concentration of nimesulide. Precision and accuracy of the method is studied. The developed differential pulse polarography method can be applied for calibration and determination of nimesulide in tablets.

Oxygen vacancy enhanced Co3O4/ZnO nanocomposite with small sized and loose structure for sensitive electroanalysis of Hg(II) in subsidence area water

Metal-oxide based nanocomposites have superior benefits to fabricate sensing interface for electroanalysis of heavy metal ions (HMIs) due to the introduction of various advantages (i.e. environmentally friendly, low-cost and high activity) into one material. Herein, Co3O4/ZnO nanocomposite with small size (sub-40 nm) and abundant oxygen vacancy was successfully prepared through one-step hydrothermal synthesis and subsequent annealing treatment, as well as the engineering of Co-Zn molar ratio. Moreover, the loose structure of Co3O4/ZnO nanocomposite can effectively improve the exposure of active sites on surface and enhance mass transfer. As a result, the as-obtained Co3O4/ZnO sensor has an impressive performance with sensitivity of 504.74 μA μM-1 cm-2 for electroanalysis of Hg(II) by square wave anodic stripping voltammetry (SWASV). Otherwise, diverse detection performances of the product with different Co:Zn molar ratio are investigated, proving the superiority for constructing Co3O4/ZnO sensor with molar ratio of 2Co/Zn. In addition, the electroanalytical behavior of the proposed sensors toward Hg(II) in subsidence area water was also realized with considerable result. By designing multifunctional nanocomposite with bimetal oxide nanomaterials, this work will provide a novel strategy to gain nanocomposite with controlling morphology and enriching oxygen vacancies, which are expected to be excellent candidate electrode materials for electroanalysis.

Engineering multi-shell Mn-Co oxide for ultrasensitive electroanalysis of Pb(II) in mining subsidence area water with promotion of adsorption and electron mediation: Behaviors and mechanisms of Mn(II)/Mn(III) and Co(II)/Co(III) cycles

It still remains unclear that the intrinsic structure-sensing property interplay of diverse transition metal oxides based sensing materials, although they have been applied in the field of environmental analysis and have achieved great progress. In this work, we performed X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) and in situ electrochemical experiment to investigate the structure-sensing interplay of Mn-Co oxide (MnCo2O4) multi-shell hiberarchy microsphere. The comprehensive studies conclusively show that the active sites on MnCo2O4 surface work as key role in determining the electrochemical behavior through the aspect of adsorption and electrocatalytic activity. In detail, the exposed oxygen on the surface of MnCo2O4 forming amounts of –OH can act as grippers to adsorb the Pb(II) in water, and then the adsorbed Pb(II) can directly occur redox in situ by the mediation of Mn(II)/(III) and Co(II)/(III) cycle on the exposed Mn and Co active sites. As a result, an excellent electroanalytical behavior (sensitivity of 120.72 µA µM−1) toward Pb(II) could be effectively improved on MnCo2O4. The fabricated electrode also showed impressive electroanalytical performance for Pb(II) in mining subsidence area. Our findings will provide new insights and effective directions for designing ultr-sensitive nanomaterials based on variable valence mediation engineering in tuning the activity of transition metal oxides.

How solution chemistry affects the electrochemical behavior of cathodes for Mg batteries, a classical electroanalytical study

Mo6S8 Chevrel phase (CP) is still the most effective magnesium ions insertion material that was examined in cathodes for rechargeable Mg battery model systems. Its synthesis includes CuMo6S8 as an intermediate which undergoes Cu ions leaching. Thereby, CP materials may contain small amounts of copper. CuxMo6S8 undergoes complex magnesium insertion processes that include reversible displacement of copper. We report herein on a study of Cu0.09Mo6S8 electrodes in two electrolyte solutions which are important for secondary Mg batteries: C6H6MgCl/AlCl3/THF (all phenyl complex solutions, APC) and MgTFSI2/MgCl2/DME (Mg imide/chloride/DME solutions, ICD). There systems are ideal playgrounds for studying the nature of complex magnesium insertion processes into inorganic hosts. The analysis reported herein shows how the electroanalytical behavior of CP electrodes is affected by the electrolyte solution identity. For instance, the main Mg ions insertion process from the APC solutions occurs at 160 mV lower than from the ICD ones; the heterogeneous rate constant for charge transfer across the interface are significantly higher in APC solutions; in turn, the conversion processes related to the Cu residue in the CP electrodes are kinetically and thermodynamically favorable in the ICD solutions. As expected, the magnesium solid-state diffusion coefficient was found to be solutions independent. The study demonstrates the sensitivity of electroanalytical tools such as slow scanning rate voltammetry for reflecting fine structural changes during intercalation processes and can be generalized to other systems.

Fabrication of nickel stamp using e-beam evaporation and electroforming for electroreduction of carbon dioxide

Electronic properties and electroanalytical behaviors are highly dependent on the morphologies of electrodes. Thus, many techniques are continuously developed to enhance carrier mobility by promoting the ordered packing of electrodes. In this work, the authors investigated the electroanalytical behavior of different prepared electrodes by controlling the morphologies of the electrodes through semiconductor-manufacturing techniques. A nickel stamp was fabricated by using photolithography, inductively coupled plasma etching, e-beam evaporation, and the electroforming technique. The stamp was used as an electrochemical electrode in a standard three-electrode cell in aqueous solution, thereby revealing the relationships among the microstructure, nickel stamp, and zinc oxide as a function of applied potential. The electrochemical reduction reaction was carried out in a conventional reactor in the presence of carbon dioxide. This reaction exhibited a higher faradaic efficiency for carbon monoxide and methane than that observed when flat nickel electrodes were used.

Electrochemical Investigation of pH‐Dependent Activity of Polyethylenimine‐Capped Silver Nanoparticles

AbstractThe pH‐dependent electroanalytical behavior and catalytic activity of branched polyethylenimine‐capped silver nanoparticles (PEI‐AgNPs) were studied by using nanoparticle collision electrochemistry, linear sweep voltammetry, and UV/Vis spectroscopy. The electrochemical collision signals respond rapidly to pH‐induced protonation of the PEI chain at the AgNP surface. This method allows for screening and catalytic activity evaluation of PEI‐AgNPs for the decomposition of organic dyes, demonstrated in this work with methylene blue. Higher oxidation of PEI‐AgNPs was observed at neutral and basic pH, when the particles are stabilized by the PEI chain. Cumulatively, these results indicate that NP collision electrochemistry can be used in addition to spectroscopy and microscopy for studying the effect of the capping agent on the electrochemical behavior of AgNPs and evaluating the relationship between the surface properties and catalytic activity. These measurements provide fundamental information about how surface characteristics, environment, and capping ligands affect NP properties and activity.

Development of electrochemical sensor for the determination of palladium ions (Pd2+) using flexible screen printed un-modified carbon electrode

To date, the development of different modified electrodes have received much attention in electrochemistry. The modified electrodes have some drawbacks such as high cost, difficult to handle and not eco friendly. Hence, we report an electrochemical sensor for the determination of palladium ions (Pd2+) using an un-modified screen printed carbon electrode has been developed for the first time, which are characterized and studied via scanning electron microscope and cyclic voltammetry. Prior to determination of Pd2+ ions, the operational conditions of un-modified SPCE was optimized using cyclic voltammetry and showed excellent electro-analytical behavior towards the determination of Pd2+ ions. Electrochemical determination of Pd2+ ions reveal that the un-modified electrode showed lower detection limit of 1.32μM with a linear ranging from 3 to 133.35μM towards the Pd2+ ions concentration via differential pulse voltammetry. The developed sensor also applied to the successfully determination of trace level Pd2+ ions in spiked water samples. In addition, the advantage of this type of electrode is simple, disposable and cost effective in electrochemical sensors.

An electrochemical biosensor based on nanoporous stainless steel modified by gold and palladium nanoparticles for simultaneous determination of levodopa and uric acid

In this paper, an electrochemical biosensor based on gold and palladium nano particles-modified nanoporous stainless steel (Au-Pd/NPSS) electrode has been introduced for the simultaneous determination of levodopa (LD) and uric acid (UA). To prepare the electrode, the stainless steel was anodized to fabricate NPSS and then Cu was electrodeposited onto the nanoporous steel by applying the multiple step potential. Finally, the electrode was immersed into a gold and palladium precursor's solution by the atomic ratio of 9:1 to form Au-Pd/NPSS through the galvanic replacement reaction. Morphological aspects, structural properties and the electroanalytical behavior of the Au-Pd/NPSS electrode were studied using field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS) and voltammetric techniques. Also, differential pulse voltammetry (DPV) was used for the simultaneous determination of LD and UA. According to results, the surface of Au-Pd/NPSS electrode contained Au and Pd nanoparticles with an average diameter of 75nm. The electrode acted better than Au/NPSS and Pd/NPSS electrodes for the simultaneous determination of LD and UA, with the peak separation potential of about 220mV. Also, the calibration plot for LD was in two linear concentration ranges of 5.0–10.0 and 10.0–55.0μmolL−1 and for UA, it was in the range of 100–1200μmolL−1. The detection limit for LD and UA was 0.2 and 15μmolL−1, respectively. The modified electrode had a good performance for LD and UA detection in urine, blood serum and levodopa C-Forte tablet.

Electroanalysis of formetanate hydrochloride by a cobalt phthalocyanine functionalized multiwalled carbon nanotubes modified electrode: characterization and application in fruits

This study characterizes the electroanalytical behavior of the carbamate pesticide formetanate hydrochloride (FMT) at a cobalt phthalocyanine (CoPc) functionalized multiwalled carbon nanotubes (fMWCNT) modified glassy carbon electrode (CoPc-fMWCNT/GCE). Nafion® was used to improve solubility and dispersibility of fMWCNT. The construction of the developed electrode was characterized by high-resolution field-emission gun scanning electron microscopy, Raman spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. FMT exhibited a behavior consistent with a three-step reaction of the electrochemical-chemical-electrochemical mechanistic type at CoPc-fMWCNT/GCE (three anodic peaks at 0.26, 0.55 and 1.2V, and two cathodic peaks at 0.35 and 0.50V vs. Ag/AgCl/3M KCl). Highly reproducible and well-defined peaks were obtained at the optimum experimental conditions (Britton-Robinson buffer at pH 5.0, accumulation potential 1.55V, accumulation time 5s, frequency 100s−1, amplitude 30mV, and scan increment 3mV). Peak currents were found to be proportional to the FMT concentrations in the range of 9.80×10−8 to 3.92×10−6moldm−3 with a detection limit (LOD) of 9.7×10−8moldm−3. The modification of GCE with CoPc-fMWCNT enhanced the electrocatalytic activity and provided high sensitivity (3.51Amol−1dm3). The developed electroanalytical methodology was successfully applied to FMT residue analysis in mango and grape samples with recoveries in the range of 94.2±4.5 to 105.7±1.8%. The proposed electroanalytical approach represents a reliable, sensitive and environmental friendly analytical alternative for determination of FMT.

Metal-Rich Transition Metal Diborides as Electrocatalysts for Hydrogen Evolution Reactions in a Wide Range of pH

Solid solutions of HfB2-ZrB2 mixtures were prepared by high-energy ball milling of diboride and additive powders followed by spark plasma sintering (SPS). A mixture of stoichiometric 1:1 HfB2-ZrB2 borides was the base composition to which Hf, Zr, Ta, LaB6 or Gd2O3 was added. Hf, Zr and Ta were added in order to bring the boron-to-metal ratio down to 1.86, rendering the boride as MeB1.86. In the case of LaB6 and Gd2O3, 1.8 mol% was added. Electroanalytical behavior of hydrogen evolution reactions was evaluated in 1 M H2SO4 and 1 M NaOH solutions. The LaB6 additive material showed Tafel slopes of 125 and 90 mV/decade in acidic and alkaline solutions respectively. The Hf and Zr rich samples showed Tafel slopes of about 120 mV/decade in both electrolytes. The overpotentials of hydrogen evolution reactions (at 10 mA/cm2) in the alkaline solution were about 100 mV lower than those in acidic solution. The metal-rich diborides and addition of LaB6 showed better hydrogen evolution reaction (HER) activities than the base 1:1 HfB2-ZrB2 stoichiometric diboride solid solution. The higher activity of metal-rich borides could be attributed to the increased electron population at the d-orbitals of the metal shown by band structure modeling calculations using the Density Functional Theory approach.