Hydrogen Evolution Overpotential Research Articles

Ferroelectric modulation of CuCo2O4 nanorods for controllable alkaline water electrolysis.

As a technology for emerging environmental applications, water electrolysis is a significant approach for producing clean hydrogen energy. In this work, we used an efficacious piezoelectric method to significantly improve the catalytic water splitting activity without affecting the morphology as well as the components by altering the bulk charge separation state inside the material. The obtained CuCo2O4 nanorods were treated under a corona polarization apparatus, which significantly enhanced ferroelectricity relative to that before the polarization increasing the physical charge separation and piezoelectric potential energy, enhancing the green hydrogen production. The polarized CuCo2O4 nanorods exhibit excellent water electrolysis performance under alkaline conditions, with hydrogen evolution overpotential of 78.7 mV and oxygen evolution overpotential of 299 mV at 10 mA cm-2, which is much better than that of unpolarized CuCo2O4 nanorods. Moreover, the Tafel slopes of polarized CuCo2O4 nanorods are 86.9 mV dec-1 in the HER process and 73.1 mV dec-1 in the OER process, which are much lower than commercial catalysts of Pt/C (88.0 mV dec-1 for HER) or RuO2 (78.5 mV dec-1 for OER), proving faster kinetic on polarized CuCo2O4 nanorods due to their higher electroconductibility and intrinsic activity. In particular, polarized CuCo2O4 nanorods are identified as promising catalysts for water electrolysis with robust stability, offering outstanding catalytic performance and excellent energy efficiency.

Facile Carbothermal Synthesis of Metal Phosphides-Based Multifunctional Electrocatalysts via Polyaniline Doped with Phosphoric Acid

Transition metal phosphides (TMPs) and their composites are promising non-platinum electrocatalysts for hydrogen evolution (HER), oxygen evolution (OER), and oxygen reduction (ORR) reactions. But traditional methods to obtain these electrocatalysts are usually multi-step and include the participation of hazardous phosphorus compounds during phosphidation. Here, the possibility of using a polyaniline doped with phosphoric acid (PANI∙H3PO4)—as a source of C, N and P simultaneously - to obtain composites based on N,P-doped carbon and nano- and/or submicron TMP particles as HER, OER and ORR electrocatalysts is demonstrated. The pyrolysis of PANI∙H3PO4 together with Co, Ni, Mo, or Fe salt allows the formation of such composite electrocatalysts by the carbon thermal reduction route. Regardless of the pH of the electrolyte, the MoP-based electrocatalyst is characterized in HER by the smallest Tafel slope and overpotential of hydrogen evolution and also exhibits high stability during long-term operation. At the same time, other composites are multifunctional electrocatalysts possessing activity not only in HER, but also in OER and ORR. The proposed approach can be a starting point for a simple, universal in choice of d-metal, and environmentally attractive preparation of multifunctional TMP-based electrocatalysts with further improvement of their performance.

Ir Nanoparticles Supported on Oxygen-Deficient Vanadium Oxides Prepared by a Polyoxovanadate Precursor for Enhanced Electrocatalytic Hydrogen Evolution.

Developing highly active electrocatalysts is crucial for the application of electrocatalytic water splitting. In this study, we prepared vanadium oxide-graphene carbon nanocomposites (VxOy/C) with abundant defects using a carbon- and oxygen-rich hexavanadate derivative Na2[V6O7{(OCH2)3CCH3}4] as a precursor without the addition of an extra carbon source. Subsequently, the VxOy/C was used as a catalyst support to load a small amount of Ir, forming the Ir/VxOy/C nanoelectrocatalyst. This catalyst exhibited low hydrogen evolution overpotentials of only 18.90 and 13.46 mV at a working current density of 10 mA cm-2 in 1.0 M KOH and 0.5 M H2SO4 electrolyte systems, outperforming the commercial Pt/C catalysts. Additionally, the catalyst showed excellent chemical stability and long-term durability. This work provides a new strategy for the design and synthesis of highly active electrocatalysts for water splitting.

Bimetallic Ni and Pt single atoms anchored on nitrogen–phosphorus doped porous carbon fibers to achieve significant electrocatalytic hydrogen evolution

The commercial application of water electrolysis for hydrogen production requires the development of low precious metal catalysts with a high crustal abundance. One feasible strategy is to utilize bimetallic catalysts composed of both transition and precious metals. In this study, a novel N/P-doped Ni/Pt bimetallic catalyst is developed (NiPt@C-NP, 3.68 % Ni, 0.2 % Pt) using polyacrylonitrile fibers as an inexpensive carbon source for catalyst support. Due to strong anchoring from the N and P heteroatoms, the nickel and platinum species are mono-atomically dispersed throughout the catalyst. Under acidic conditions, NiPt@C-NP exhibits a hydrogen evolution overpotential of 89 mV (10 mA cm−2), whereas an unsupported platinum catalyst gives an overpotential of 302 mV. The mass activity of Pt in NiPt@C-NP reaches 36.17 A mgPt−1, which is 33 times higher than 20 % Pt/C (1.07 A mgPt−1). Density functional theory (DFT) calculations reveal that synergistic interactions between Ni and Pt significantly increase the density of state near the Fermi level of NiPt@C-NP, resulting in a reduced bandgap and an enhanced charge transfer capability. Furthermore, the Gibbs free energy at the Pt and Ni sites is − 0.25 and − 0.63 eV, respectively, indicating fast reaction kinetics.

In-situ growth 2D Fe2P nanosheets on the surface of 1D Cd0.9Zn0.1S nanorods for remarkably improved photocatalytic H2 evolution

Loading cocatalysts can effectively reduce the hydrogen production overpotential and provide additional catalytic sites. Fe2P, with abundant active sites, low hydrogen evolution overpotential, is regarded as a promising cocatalyst to replace the noble metals. Fe2P nanosheets were grown in situ on the surface of Cd0.9Zn0.1S nanorods to form unique 2D/1D structure, which was designed to enlarge the interface contact between them. The maximum hydrogen evolution rate was as high as 38.48 mmol h−1 g−1, which was even higher than that of noble metal Pt modified Cd0.9Zn0.1S. The results of characterization and theoretical computation demonstrated that the electronic interaction existed between Fe2P and Cd0.9Zn0.1S, and Fe2P as cocatalyst collected electrons to facilitate the transfer and separation of electrons and holes. This work investigated the transfer process of photogenerated carriers and revealed the photocatalytic mechanism through a combination of theoretical calculation and experimental characterization.

Stable overall water electrolysis performance of interface engineered Y2Ru2O7/NiMoO4@NF in alkaline solution

Problems faced in water electrolysis, such as sluggish reaction kinetics and poor electrode stability, can be overcome by developing electrode materials with tailormade properties. Introducing a nanostructured interface with pyrochlore materials is an efficient but complex strategy. This study focused on the interface engineering of the pyrochlore Y2Ru2O7/NiMoO4@NF. The material was found to show significantly high overall water splitting performance in 1 M KOH electrolyte solution. Specifically, the prepared Y2Ru2O7/NiMoO4@NF showed oxygen evolution and hydrogen evolution overpotentials of 287 and 112 mV at a current density of 10 mA cm−2, respectively. A Y2Ru2O7/NiMoO4@NF electrode with higher stability that was prepared rationally required a cell voltage of only 1.613 V to achieve a current density of 10 mA cm−2 for alkaline water electrolysis. This showed the excellent catalytic ability of the electrode for overall water splitting. In particular, the temperature dependence of the electrode’s performance in water electrolysis in a practical water electrolyzer was examined to ascertain the electrode’s suitability for use on an industrial scale; the operating temperature of the electrolyzer was varied in the range 25–75 °C. The observed exceptional alkaline overall water splitting performance of the electrode resulted from the high charge mobility at the interface that enhanced synergy between Y2Ru2O7 and NiMoO4. The results of this study show that combining the metal oxides Y2Ru2O7 and NiMoO4 is a promising approach for preparing materials with high catalytic activity for use in alkaline overall water splitting.

Pulse and Pulse/Reverse Techniques for Electrodeposition of Rhenium and Refractory Metals

Refractory metals possess unique properties including high melting points, high hardness at room temperature, chemical resistance, and high density. Electrodeposition of refractory metals is of interest as a scalable approach to apply uniform coatings to enable a wide range of applications in aerospace, nuclear, catalysis, biomedical fields. This talk will focus on pulse electrochemical variables to enable methods to electrodeposit high quality metallic rhenium (Re).Re has traditionally been difficult to deposit from aqueous solutions due to the over potential for hydrogen evolution and complex electrochemical reactions. Electrodeposition of rhenium usually occurs from the perrhenate ion (ReO4-) with an oxidation state of +7. The exact mechanism to reduce the perrhenate ion from +7 to metallic rhenium is still unknown. It is unlikely that the 7 electrons transfer in a single step, so reduction likely occurs through intermediate oxide species including ReO2, ReO3 and Re2O5. Combined with the hydrogen evolution reaction, Re coatings are generally deposited at low faradaic efficiency, are brittle, and limited in thickness (sub-micron). In our previous work, water-in-salt electrolytes and complexing additives have enabled resolution of some of the issues associated with this complexity and a range of deposit qualities, though cracking issues remain and coating quality issues still needed optimization.Herein, we present on the effects of pulsed electrochemical approaches to eliminate cracking in the film by balancing nucleation and growth and the competing hydrogen evolution reaction. A custom high-throughput cell was developed to rapidly screen parameters and explore time-dependent evolution of the electrodeposition processes.

Redox Behavior of Arsenic (III) and Copper (II) Mixtures on Ultraflat Au (111) Thin Film Electrodes

The electrochemical behavior of arsenic on gold (Au) electrodes surfaces is of great interest as As is well-recognized as a highly toxic and relatively ubiquitous ground water species. The United States Environmental Protection Agency (USEPA) and World Health Organization (WHO) drinking water standards for arsenic are 10 PPB, or 𝜇g L-1 [1]. These minute ion concentrations necessitate the use of analytical methods with high sensitivity and a low susceptibility to cross interferences. Electrochemical stripping voltammetry is a well-established electroanalytical method for arsenic ions [2]. Polycrystalline gold electrodes are often used due to their high redox stability and relatively low overpotential for hydrogen evolution. We recently explored the use of ultra-flat, thin film, Au(111) electrodes to replace polycrystalline Au for As stripping voltammetry. Previous studies on oriented single crystals showed relatively narrow stripping peaks with greatly improved peak to background ratios on the (111) surfaces [3]. We observed comparatively similar or better stripping behavior on the Au(111) thin film electrodes with correspondingly far less gold usage per electrode. Unfortunately, copper is a known interference for arsenic stripping electroanalysis, with a strong affinity for UPD deposition on gold. We therefore studied the deposition behavior of Cu on Au(111) thin film electrodes and the co- deposition of Cu and As on the Au(111) thin film electrodes to evaluate cross interference effects. Copper redox behavior in 0.5M H2SO4 was characterized by cyclic voltammetry, electro- deposition and linear stripping voltammetry (LSV) measurements. Strong Cu UPD behavior was observed on Au(111) thin films with sharper, better defined redox peaks than polycrystalline electrodes. Arsenic and Cu ions were also co-deposited over a wide range of Cu (II) and As (III) concentrations. Complex redox behavior was observed with strong indications of Cu-As alloy formation. This was confirmed via angle resolved, X-ray Photoemission Spectroscopy (XPS) measurements. Our results also indicate that the electrodeposition efficiency during LSV of As is increased by the co-deposition of Cu. The results of this study have important implications for understanding the nature of Cu (II) interference with electrochemical detection of trace As (III) in water.[1] USEPA. National Secondary Drinking Water Regulations. 2009. https://www.epa.gov/sdwa/drinking-water- regulations-and-contaminants (accessed.[2] USEPA. METHOD 7063: ARSENIC IN AQUEOUS SAMPLES AND EXTRACTSBY ANODIC STRIPPING VOLTAMMETRY (ASV). 1996.[3] Casuse-Driovínto, T. Q.; Rizo, R.; Benavidez, A.; Brearley, A. J.; Cerrato, J. M.; Garzon, F. H.; Herrero, E.; Feliu, J. M. Increased Sensitivity and Selectivity for As(III) Detection at the Au(111) Surface: Single Crystals and Ultraflat Thin Films Comparison. The Journal of Physical Chemistry C 2022, 126 (48), 20343-20353. DOI: 10.1021/acs.jpcc.2c05541.

Nickel-Based Bifunctional Cocatalyst to Enhance CdS Photocatalytic Hydrogen Production.

The design of nanocomposites as a light-capturing system applied in photocatalytic water splitting is an emerging area of research. In our study, a simple in situ photodeposition method was proposed for the synthesis of CdS nanoflowers modified by nickel-based bifunctional, i.e., Ni/Ni(OH)2, cocatalysts. The introduction of cocatalysts has demonstrated a notable enhancement in the photocatalytic hydrogen evolution efficiency of CdS. The quantity of cocatalysts supported on CdS played an important role in governing the light absorption capability and photocatalytic efficacy. Ni-CdS-10 showed the best photocatalytic activity of 30.51 mmol g-1 h-1, which was 1.8 times and 2.6 times higher activity than Pt-CdS-1 wt % and pure CdS, respectively. Mechanism studies with UV-vis DRS, photoluminescence, and Mott-Schottky plots revealed the intrinsic electric field created at the p-n Ni(OH)2/CdS junctions, which can effectively implement the transport and separation of photoinduced carriers. From linear sweep voltammetry, electrochemical impedance spectroscopy, and DFT calculation, both Ni(OH)2 and Ni can effectively decrease the Gibbs free energies of hydrogen adsorption and reduce the overpotential of hydrogen evolution. As a result, the efficiency of generating H2 through photocatalysis experienced significant improvement, and the participation of bifunctional cocatalysts further reduced the photocorrosion of CdS, enhanced stability, improved low price, and efficient photocatalyst production.

In situ Construction of Multifunctional Surface Coatings on Zinc Metal for Advanced Aqueous Zinc–Iodine Batteries

AbstractAqueous zinc–iodine batteries (Zn–I2) demonstrate great promise in large scale energy storage systems. However, their practical application faces significant challenges including dendrite formation, corrosion caused by polyiodine ions, and other side reactions at the zinc anode side. Herein, a facile and efficient pretreatment method for zinc anodes through the substitution reaction of Zn and SnF2 to create a dense and durable multifunctional surface layer (MSL). The MSL comprise tin (Sn) and ZnF2 phases on the zinc metal, in which Sn possesses good zinc affinity and a high hydrogen evolution overpotential, while ZnF2 provides pathways for radial ion transport. Importantly, both have a low binding energy with polyiodine ions, preventing the failure of the interface layer. Therefore, this interface layer can effectively mitigate zinc metal electrode dendrite formation, corrosion from polyiodine ions, and other side reactions induced by water, simultaneously. As a result, the Zn–I2 batteries performance is greatly improved and exhibited a stable cycling to 20 000 times with 80% capacity retention at a current density of 2 A g−1. Even the I2 loading is increased to 8 mg cm−2, it can still cycle stably for 5000 cycles with a capacity retention of 94%.

High-efficient synthesis of NaBH4 by solid-phase electrolysis process on a core-shell-type cathode

NaBH4 is a promising hydrogen storage material, while faced with enormous difficulties for scale-up application due to regeneration issues. In this study, a highly efficient and economical strategy for the electrosynthesis of NaBH4 from hydrolysis by-product NaB(OH)4 has been proposed. By fabricating solid-phase electrodes with NaB(OH)4 and electrocatalyst etc., the mass transfer process of B(OH)4- at the cathode surface was remarkably improved, thus reducing the resistance of the cathodic reaction. Meanwhile, XPS, FTIR, and CV analyses were combined to reveal the reaction path and control steps of B(OH)4- reduction to BH4− in the electrocatalytic system. The formation of NaBH4 and intermediates (BH(OH)3-, BH2(OH)2-, and BH3(OH)-) is the gradual replacement of (OH)- in NaB(OH)4 by H−. Furthermore, this study reveals that PbO has a suitable hydrogen evolution overpotential and excellent selective catalytic activity. The current efficiency for NaBH4 synthesis via solid-phase electrolysis was up to 68.12 % by systematically regulating various factors.

Smoothing effect of H3BO3 on hydrogen evolution catalyst and the promotion of hydrogen evolution

Hydrogen is a vital clean energy, and reducing overpotential in hydrogen evolution has become necessary research, in which CoMo bimetal material is a promising high-efficiency hydrogen evolution material. In this study, boron was added to MoCo bimetallic ion catalysts with carbon cloth and copper foil substrates, and it was found that adding boron could significantly reduce the hydrogen evolution overpotential of the catalysts. The morphology analysis by SEM showed that the addition of boric acid in the electrolyte could change the morphology of the catalyst, making the surface of the catalyst smooth and uniform distribution on the carrier, while the surface of the catalyst without boric acid formed agglutination. The prepared CoMoB-CC catalyst has an overpotential of 44.1 mV when the current density is -10 mA·cm−2. This paper primarily presents interesting phenomenon of the smooth effect of boric acid on the catalytic electrode, and the prepared catalyst has good catalytic performance, which provides some help for the preparation of hydrogen evolution materials.

Hetero Nucleus Growth Stabilizing Zinc Anode for High-Biosecurity Zinc-Ion Batteries

HighlightsAnimal models are applied to evaluate the biosecurity and biocompatibility of the zinc-ion batteries with the electrolytes of different zinc salts.Leakage scene simulations and histological analysis are employed in investigating the tissue response after battery implantations, in which ZnSO4 exhibits higher biosecurity.Sn hetero nucleus is introduced to stabilize the zinc anode, which not only facilitates the planar zinc deposition, but also contributes to higher hydrogen evolution overpotential.

Application of carbon fibers in thin-plate pure lead batteries

BackgroundThis research aimed to synthesize a Pb/CF cloth/Pb composite as a highly efficient lead-carbon electrode for lead-acid batteries (LAB). Degradation of lead–acid batteries (LAB) often results from intermittent renewable energy usage. The addition of carbon materials can help inhibit LAB degradation. Thin plates made of pure Pb exhibit a high hydrogen evolution overpotential and greater resistance to corrosion than Pb alloys in dilute H2SO4. Meanwhile, activated CF cloth is a monolithic, conductive, and hydrophilic material. However, carbon materials are chemically inert making the Pb/C interface with high resistance and tend to have a lower hydrogen evolution overpotential. MethodsFollowing chemical modification, activated CF cloth was used to fabricate LCF through hot pressing. The formation mechanism of LCF was then determined by analyzing the surface characteristics of the CF cloth after chemical modification. Significant findingsThe inner CFs in LCF were wetted by liquid Pb. The charge transfer resistivity (Rct) of LCF was 18.82 Ω, which is considerably lower than that of Pb (616.80 Ω). Both pure LCF and paste-type LCF AGM batteries exhibit notable charge acceptance during HRPSoC cycling. The remaining 1C capacity of paste-type LCF battery remains stable over 1000 cycles with high 1C rate charge and 3C rate discharge cycling.

Decoupling the anodic and cathodic behavior in asymmetric electrochemical hydroiodic acid decomposition cell for hydrogen production in the iodine-sulfur thermochemical cycle.

The HI section of the iodine-sulfur (I-S) thermochemical cycle for hydrogen production is one of the most energy-intensive sections and with significant material handling challenges, primarily due to the azeotrope formation and the corrosive nature of the hydroiodic acid-iodine-water mixture (HIx). As an alternative, the single-step direct electrochemical decomposition of the hydroiodic acid (HI) to generate hydrogen can circumvent the challenges associated with the conventional multistep HI section in the I-S cycle. In this work, we present new insights into the electrochemical HI decomposition process by deconvoluting the contributions from the anodic and the cathodic sections in the electrochemical cell system, specifically, the redox reactions involved and the overpotential contribution of the individual sections (anolyte and catholyte) in the overall performance. The studies on the redox reactions indicate that the HIx solution output from the Bunsen reaction section should be used as the anolyte. In contrast, aqueous HI without any iodine (I2) should be used as the catholyte. In the anodic section, the oxidation proceeds with I2 as the final oxidized species at low bias potentials. Higher positive potentials result in iodate formation along with oxygen evolution. For the catholyte section, I2 and tri-iodide ion reduction precede the hydrogen evolution reaction when I2 is present along with HI. Furthermore, the potential required for hydrogen production becomes more negative with an increasing I2/HI ratio in the catholyte. Polarization studies were conducted with simultaneous deconvolution of the anodic and cathodic behavior in a two-compartment cell. Model fitting of the polarization data revealed that the anolyte section's activation overpotential is negligibly low. In contrast, the activation overpotential requirement of the catholyte section is higher and dictates the onset of hydrogen production in the cell. Furthermore, the catholyte section dominates the total overpotential losses in the cell system. Operation in the ohmic resistance-dominated zone resulted in close to 90% current efficiency for the electrochemical HI decomposition. The results highlight that the potential for process improvement lies in reducing the ohmic resistance of the anolyte section and in lowering the activation overpotential of hydrogen evolution in the catholyte section.

Mitigating water-related challenges in aqueous zinc-ion batteries through ether-water hybrid electrolytes

Aqueous zinc-ion batteries (AZIBs) are an attractive option for different energy storage applications due to their cost-effectiveness, safety benefits, and high capacity. Nevertheless, their development is constrained by challenges such as hydrogen evolution reaction (HER), significantly affecting the battery lifespan. This work presents a promising solution to this problem using a hybrid electrolyte, consisting of water and tetra ethylene glycol dimethyl ether (TEGDME) containing Zn(OTf)2. Results demonstrate that this hybrid electrolyte can suppress HER and can lessen zinc corrosion by reorienting hydrogen bonds with water and actively participating in the solvation structure of Zn2+ ions. Such reorientation reduces water activity and weakens the interactions between water molecules and between water and Zn2+ ions. By employing an optimal TEGDME/H2O ratio of 2:1 in the hybrid electrolyte, hydrogen evolution overpotential increased by 0.26 V. As a result, in the Zn//Zn symmetrical cells, the developed hybrid electrolyte is seen to enable the Zn electrode to exhibit excellent cycle durability, lasting over 4300 h with coulombic efficiency (CE) of 99.68% at 0.5 mA cm−2 and 0.5 mAh cm−2, surpassing the 92.79% achieved by the base electrolyte (1 M Zn(OTf)2 aqueous solution) cells. Moreover, when implemented in Zn/δ-MnO2 batteries, the hybrid electrolyte maintained its performance for over 1800 cycles at a discharge rate of 100 mA g−1. This cost-effective and adaptable strategy highlights its wide-ranging potential, offering vital insights for the enhancement of AZIB technology.

Rhenium Electrodeposition to Enable Functionally Graded Films

Rhenium (Re) has one of the highest melting points of all the metals with a high modulus of elasticity and superior tensile strength when compared to other refractory metals. However, processing challenges from the high temperature stability combined with the relative occurrence require advanced manufacturing approaches to leverage the unique properties of rhenium. The electrodeposition of rhenium has received renewed attention in the past decade as a scalable approach to apply uniform coatings to enable a wide range of applications in aerospace, nuclear, catalysis, biomedical fields. However, Re has traditionally been difficult to deposit by electrolysis from aqueous solutions due to the over potential for hydrogen evolution and complex electrochemical reactions.Beginning with the perrhenate anion (ReO4 -), reduction from the +7 oxidation state must occur to deposit metallic Re. The exact mechanism of this process is still unknown with reductions to ReO2, ReO3, and Re2O5 along with metallic Re. Combined with the hydrogen evolution reaction, Re coatings are generally deposited at low faradaic efficiency, are brittle, and limited in the obtainable thickness (sub-micron).Herein, we present systematic studies progressing towards the development of stable and efficient electrolytes to enable the electrodeposition of thick (100+ microns) Re coatings. Borrowing the water-in-salt electrolyte method from the lithium battery literature enables near room-temperature electrodeposition of Re. Specifically, we correlate nucleation and growth mechanisms of Re with the ability produce thick coatings. Pulse/pulse reverse electroplating was applied to manipulate the obtained grain structure and distribution of rhenium moieties. Correlations between the electrolyte composition and the pulse parameters with the observed morphology will be discussed with an emphasis on enabling industrially relevant electroplating processes.The goal of this project is the electrodeposition of rhenium-cobalt (Re-Co) graded compositional/density samples of millimeter thickness. Thus, understanding how to transition from a coating or pure metallic rhenium to a graded composition of Re-Co as a function of dynamic processing conditions will be presented.

Study of CuO/TiO2/Polyindole (CTPIN) electrocatalyst in membraneless electrolyzer for solar hydrogen generation

Efficient electrocatalysts are indispensable for promoting the hydrogen evolution reaction (HER). Existing electrocatalysts are limited by sluggish HER kinetics, higher over potential leading to greater energy demand, instability over time, and low tolerance to impurities. These challenges lead to a lower solar-to-hydrogen conversion efficiency of 2.46% using MoS2 electrocatalyst in authors’ previous research work. Mixed metal oxide/conducting polymer nanocomposites have shown great potential for use in hydrogen evolution reaction (HER) reactors due to their high surface area, excellent catalytic activity, and stability in acidic and alkaline environments. A major requirement for suitable electrocatalyst is a low overpotential for hydrogen evolution, a high tolerance to impurities and a long-term durability which makes it more efficient than traditional electrocatalysts. With this brief background, the present work focuses on the application of CuO/TiO2/Polyindole (CTPIN) nanocomposite synthesized with the help of two-step process involving microemulsion and oxidative polymerization techniques. The resulting material was characterized using miscellaneous physicochemical techniques. HRTEM analysis clearly demonstrates the formation of CTPIN nanocatalysts with ultrasmall particle sizes of 10–30 nm. The nickel strip was coated with CTPIN nanoparticles was used as cathode for generating solar hydrogen through membraneless electrochemical water splitting. Membraneless electrolyzers offer a promising and cost-effective substitute to traditional electrolyzers, enabling efficient electrochemical hydrogen generation. At a radiation intensity of 320 W/m2 and under normal working conditions, the CTPIN nanocomposite demonstrated a solar-to-hydrogen generation efficiency of 3.43% which is greater than previous results obtained using MoS2. The CTPIN electrocatalyst has a high potential for electrocatalytic solar hydrogen generation. The CTPIN electrocatalyst could make it possible to produce hydrogen from clean and renewable energy source.

Nitrogen-doped Ni3P–NiMoO4 heterostructure arrays for coupling hydrogen production with polyethylene terephthalate plastic electro-recycling

The global plastic pollution problem has seriously affected the survival of natural and human organisms. Electrochemical polyethylene terephthalate (PET) plastic reforming powered by renewable electricity, is expected to provide an environmentally friendly, convenient, and efficient way to recycle plastics. Herein, we synthesized a heterostructure array catalyst of nitrogen-doped Ni3P–NiMoO4 on nickel foam (N–Ni3P–NiMoO4/NF) for coupling PET waste plastic electro-recycling and hydrogen production. Due to the rich catalytic active sites provided by the heterogeneous interface structure, N–Ni3P–NiMoO4/NF can achieve a low hydrogen evolution overpotential of 142 mV with a current density of 100 mA cm−2. The PET hydrolysate-containing electrolyte had a potential of 194 mV lower than that of conventional water splitting at a current density of 100 mA cm−2 and catalyze the conversion of PET hydrolysate to formate efficiently with a maximum Faraday efficiency of 92.2%. This work provides a new strategy and approach for upcycling resource utilization and energy-saving hydrogen production of PET waste plastic.

Synthesis of Ternary Cross-Linked MoS2/WS2/CdS Photocatalysts for Photocatalytic H2 Production

Photocatalytic H2 production provides an ideal way to alleviate the energy crisis and solve environmental problems. In this paper, the metallic MoS2/WS2 dual cocatalysts are prepared through the in situ growth of 1T-WS2 on the surface of 1T-MoS2 via a solvothermal method. The ternary cross-linked MoS2/WS2/CdS photocatalysts are finally constructed by growing CdS nanorods on MoS2/WS2 cocatalysts. The XRD and TEM results show that ternary cross-linked MoS2/WS2/CdS photocatalysts with close interfacial contact were successfully synthesized. The results of Photoluminescence (PL) and photoelectrochemical tests show that MoS2/WS2/CdS has the lowest hydrogen evolution overpotential and the highest charge separation efficiency. This is due to the synergistic effect between WS2 and MoS2, which further accelerates the transfer of photogenerated electrons and inhibits the recombination of carriers. The hydrogen evolution rate of the MoS2/WS2/CdS composite is 12.12 mmol·g−1·h−1, which is 4.57 times that of pristine CdS. The AQY at λ = 420 nm is 58.9%.