Fast Charge Transfer Kinetics Research Articles

Immobilization of PCET Materials for Electrochemical pH Swing Driven Carbon Capture

Proton-coupled electron transfer (PCET) is a promising method in the realm of carbon capture and release mechanisms. Its fundamental capacity lies in electrochemically inducing pH swings within an aqueous solution, leveraging the high solubility of carbonates in highly alkaline water to capture CO2 and subsequently release iton demand when the aqueous solution is acidified. PCET-based methods promise higher energy efficiency for carbon capture compared to other electrochemical carbon capture methods because they feature fast charge transfer kinetics and can decouple gas-liquid contact and electrochemical activation. In theory, they also allow the use of cheap, widely available small-molecule PCET agents. However, in practice, PCET agents have shown a key limitation that has, thus far, hindered their scalability: oxygen-induced chemical degradation with continued electrochemical cycling. In this work we mitigate the prevailing issue of oxygen sensitivity by immobilizing PCET agents onto a fabric substrate. Via reactive vapor deposition (RVD), porous and conductive films composed of PEDOT-Cl and poly-aminoanthroquinone (PAAQ) are deposited on the surface of a wool felt blend fabric. This approach resulted in the development of a cost-effective, metal-free, and efficient electrode for both capture and release of CO2. Through electrochemical evaluation, the performance of PCET-active quinone moieties present on PAAQ was measured. The overall efficiency of electrochemical capture from gaseous CO2 was found to be 197 kJ/molCO2, substantiating the efficacy of this novel electrode. This work highlights the potential of fabric-immobilized PCET agents and presents a promising avenue towards a sustainable, efficient, and economically viable approach to carbon capture and release technologies.

Efficient degradation of methylene blue and ciprofloxacin compounds using heteroanionic titanium oxycarbide photocatalyst and its correlation with their dielectric properties

In recent times, semiconductor-based photocatalysts have emerged as a promising solution for remediating water pollutants. This study contributes to this field by successfully preparing a heteroanionic titanium oxycarbide photocatalyst, denoted as TiO0.5C0.5 (TiOC), through a solid-state reaction. The structural, morphological, optical, vibrational, and chemical bonding properties of TiOC were thoroughly characterized using XRD, TEM, SEM-EDS, UV–Vis DRS, FT-IR, and XPS. The photocatalytic activity of TiOC was evaluated by degrading methylene blue (MB) and ciprofloxacin (CP) under visible light (VL) irradiation in different water sources (deionized, domestic tap, and seawater). Notably, TiOC achieved significant degradation efficiencies of 79 % for MB and 82 % for CP within 180 minutes under VL in deionized water. However, its efficiencies were lower in tap water (65 % for MB, 72 % for CP) and seawater (57 % for MB, 56 % for CP) due to the presence of interfering substances (inorganic ions, radical scavengers), varying initial pH, and salinity. Additionally, dielectric permittivity measurements of TiOC at room temperature revealed a high dielectric constant (ε' ≈ 179), facilitating efficient exciton separation. Its high loss tangent (ε'' ≈ 10) is attributed to improved conductivity, enabling faster charge-carrier transfer kinetics, which contributes to the enhanced removal of MB and CP. Overall, the enhanced removal efficacy of MB and CP using TiOC is attributed to the synergistic effects of enhanced VL absorption, faster charge transfer kinetics, improved exciton separation, and a favorable pH environment.

Single step grown porous polycrystalline nickel microstructures with ultra-thin defect rich surface oxide for alkaline water oxidation

Investigation on the intrinsic catalytic activity of structurally diverse polycrystalline nickel microstructures such as porous nickel sheets (PNS), porous folded/curled nickel structures (PFNS) and porous nickel balls (PNB) revealed the surface bounded electrocatalytic activities within an alkaline reaction environment for water oxidation. Nickel microstructures were grown via template/surfactant-free, single step solution combustion technique in air atmosphere. The distinct morphologies (porous nickel sheets, porous folded/curled nickel structures and porous nickel balls) were achieved through changing the quantity of HNO3 in the reaction mixture. The physicochemical characterisations were done with XRD, FESEM, EDS and XPS. Microscopic studies revealed the growth of nickel grains with numerous macro pores forming microstructures in distinct morphologies. The O ls spectra of XPS studies revealed the presence of O−/O2− sites and Ni 2p spectra were distinguished between the formation of Ni0/Ni2+/Ni3+ states, implied the existence of surface oxide with plenty of defects. The synergistic effect results from the formation of microscopic porous architectures with defect rich surface oxide on the electrochemical behaviour and OER activity of PNS, PFNS and PNB were discussed with electrochemical techniques such as CV, LSV, EIS and CP. The OER kinetics in terms of relatively low value of overpotential at 10 mA cm−2 and Tafel slope along with high specific activity of PNS/GCE with respect to PFNS/GCE and PNB/GCE were attributed to the combined effect of increase in electrochemical surface area, high roughness factor and fast charge transfer kinetics. The better electrochemical performance and OER activities of porous nickel sheets in comparison with folded/curled nickel structures and nickel balls is contributed to the unique 2D porous architecture with plenty of oxygen vacancies. This structure not only expose more surface for the formation of passive oxide layer in an alkaline reaction environment but also exhibit facile charge transport properties, causes the generation of numerous surface-active sites for electrocatalytic water oxidation. The outcome of our work gives new insights on the surface electrochemistry of polycrystalline nickel, enables micro-structuring as a prospective strategy towards the optimization of electrocatalysts as anode material for alkaline water oxidation.

Pd-substitution impact in nickel–cobalt spinel oxide grown on Ni foam as very effectual electrocatalyst for green hydrogen production supported by DFT study

The hydrothermal preparation of catalytic NiPdxCo2-xO4 (x ≦ 0.08) nano-electrocatalysts on Ni foam (NF) was successfully accomplished. The morphology and chemical composition of the catalysts are confirmed by advanced analytical techniques XRD, SEM, EDX, TEM, HR-TEM, and XPS. The NiPdxCo2-xO4 (x = 0.06) NF nano-electrocatalyst demonstrated remarkable performance in the HER, with an overpotential of 191.6 mV, a Tafel slope of 84.7 mV/dec, and extraordinary stability over 24 h using chronopotentiometry methods. The surface and electrochemical analyses demonstrated that the sample, doping with a 6.0% Pd2+ concentration, had appreciably enhanced performance in the HER. The improvement may be attributed to a much larger electrochemical surface area and fast charge transfer kinetics at the semiconductor and electrolyte interface. The influence of Pd dopants on the HER performance of CNs is studied with the help of density functional theory. It elucidates the way in which hydrogen and water molecules bind to the surface of PCN slabs. The theoretical results suggest that the incorporation of Pd dopants enhances the electrocatalytic process and boosts the HER activity as the concentration of Pd increases. The density of state spectra reveals their effect on spin-dependent electronic structure characteristics. Our findings point to a practical path for creating distinctive electrocatalysts that will serve as better electrodes for a variety of forthcoming hydrogen fuel cell applications.

Fast Outer-Sphere Electron Transfer and High Specific Capacitance at Covalently Modified Carbon Electrodes.

Carbon electrodes typically display sluggish electron transfer kinetics due to the adsorption of adventitious molecules that effectively insulate the surface. Here, we describe a method for rendering graphitic carbon electrodes permanently hydrophilic by functionalization with 4-(diazonium)benzenesulfonic acid. In aqueous electrolytes, these hydrophilic carbon electrodes exhibit metal-like specific capacitance (∼40 μF/cm2) as measured by cyclic voltammetry, suggesting a change in the double-layer structure at the carbon surface. Additionally, the modified electrodes show fast charge transfer kinetics to outer-sphere one-electron redox couples such as ferro-/ferricyanide as well as improved electron transfer kinetics in alkaline aqueous redox flow batteries.

Metal-Organic Framework-Derived Co9S8 Nanowall Array Embellished Polypropylene Separator for Dendrite-Free Lithium Metal Anodes.

Developing a reasonable design of a lithiophilic artificial solid electrolyte interphase (SEI) to induce the uniform deposition of Li+ ions and improve the Coulombic efficiency and energy density of batteries is a key task for the development of high-performance lithium metal anodes. Herein, a high-performance separator for lithium metal anodes was designed by the in situ growth of a metal-organic framework (MOF)-derived transition metal sulfide array as an artificial SEI on polypropylene separators (denoted as Co9S8-PP). The high ionic conductivity and excellent morphology provided a convenient transport path and fast charge transfer kinetics for lithium ions. The experimental data illustrate that, compared with commercial polypropylene separators, the Li//Cu half-cell with a Co9S8-PP separator can be cycled stably for 2000 h at 1 mA cm-2 and 1 mAh cm-2. Meanwhile, a Li//LiFePO4 full cell with a Co9S8-PP separator exhibits ultra-long cycle stability at 0.2 C with an initial capacity of 148 mAh g-1 and maintains 74% capacity after 1000 cycles. This work provides some new strategies for using transition metal sulfides to induce the uniform deposition of lithium ions to create high-performance lithium metal batteries.

Ion-irradiation induced structural, electronic, and optical properties modification in a few layered MoS2

Two-dimensional MoS2 is a promising candidate due to its layered structure, high conductivity, and fast charge transfer kinetics. In this work,the structural, electronic, and optical properties of pristine MoS2 have to be done by the ion irradiation technique with different ion fluences.The structural quality of the film has been confirmed by Raman spectroscopy, with peak positions of A1g and E12g indicating a few MoS2 layers. Fourier-transform infrared (FTIR) spectroscopy revealed the conformal fabrication of MoS2 nanosheets. Defect engineering by ion irradiation is an effective approach to tuning the intrinsic properties of Layered MoS2, as analyzed by photoluminescence spectroscopy.

Boosting the Proton Intercalation via Crystal Plane Optimization of TiS2 for Cycling‐Stable Aqueous Zn‐Ion Batteries

AbstractTiS2 has received significant attention as a promising anode for “Rocking‐Chair”‐type aqueous Zn‐ion batteries due to the large interlayer spacing and low discharge plateau. However, the structural distortion caused by the embedding of divalent Zn2+ as well as the undesirable hydrogen evolution reaction (HER) severely affects their cycling stability. Herein, a facet‐dependent mechanism is first deeply investigated to understand charge storage behaviors of TiS2 via differential electrochemical mass spectrometry, in situ electrochemical quartz crystal microbalance, and in situ X‐ray diffraction characterizations. By regulating the exposed crystal facets of TiS2 from (001) (TS (001)) to (011) (TS(011)), HER can be effectively inhibited, and the charge storage mechanism is transformed from Zn2+ insertion/extraction dominating to H+ insertion/extraction dominating, resulting in faster charge transfer kinetics and strong structure stability during long‐term cycling. Hence, TS(011) delivers a higher reversible capacity of 212.9 mAh g−1 at 0.1 A g−1 and a strong cycling stability of 74% capacity retention over 1000 cycles, much better than that of TS (001) with a reversible capacity of 164.7 mAh g−1 at 0.1 A g−1, a capacity retention of 17% after 1000 cycles. These new findings can provide deep insight into the rational design of high‐performance intercalation‐type electrode materials for energy storage applications.

Activation of MnO6 Units via an Interfacial Electric Field: Electron Injection into Mn t2g for Rapid and Stable Sodium Ion Storage in CeO2/MnOx.

Manganese-based oxides (MnOx) suffer from sluggish charge diffusion kinetics and poor cycling stability in sodium ion storage. Herein, an interfacial electric field (IEF) in CeO2/MnOx is constructed to obtain high electronic/ionic conductivity and structural stability of MnOx. The as-designed CeO2/MnOx exhibits a remarkable capacity of 397 F g-1 and favorable cyclic stability with 92.13% capacity retention after 10,000 cycles. Soft X-ray absorption spectroscopy and partial density of states results reveal that the electrons are substantially injected into the Mn t2g orbitals driven by the formed IEF. Correspondingly, the MnO6 units in MnOx are effectively activated, endowing the CeO2/MnOx with fast charge transfer kinetics and high sodium ion storage capacity. Moreover, In situRaman verifies a remarkably increased structural stability of CeO2/MnOx, which is attributed to the enhanced Mn─O bond strength and efficiently stabilized MnO6 units. Mechanism studies show that the downshift of Mn 3d-band center dramatically increases the Mn 3d-O 2p orbitals overlap, thus inhibiting the Jahn-Teller (J-T) distortion of MnOx during sodium ion insertion/extraction. This work develops an advanced strategy to achieve both fast and sustainable sodium ion storage in metal oxides-based energy materials.

Crystal reconstruction of V2O3/carbon heterointerfaces via anodic hydration for ultrafast and reversible Mg‐ion battery cathodes

AbstractMagnesium‐ion batteries (MIBs) have promising applications because of their high theoretical capacity and the natural abundance of magnesium Mg. However, the kinetic performance and cyclic stability of cathode materials are limited by the strong interactions between Mg ions and the crystal lattice. Here, we demonstrate the unique Mg2+‐ion storage mechanism of a hierarchical accordion‐like vanadium oxide/carbon heterointerface (V2O3@C), where the V2O3 crystalline structure is reconstructed into a MgV3O7∙H2O phase through an anodic hydration reaction upon first cycle, for the improved kinetic and cyclic performances. As verified by in situ/ex situ spectroscopic and electrochemical analyses, the fast charge transfer kinetics of the V2O3@C cathode were due to the crystal‐reconstruction and chemically coupled heterointerface. The V2O3@C demonstrated an ultrahigh rate capacity of 130.4 mAh g−1 at 50 000 mA g−1 and 1000 cycles, achieving a Coulombic efficiency of 99.6%. The high capacity of 381.0 mA h g−1 can be attributed to the reversible Mg2+‐ion intercalation mechanism observed in the MgV3O7∙H2O phase using a 0.3 M Mg(TFSI)2/ACN(H2O) electrolyte. Additionally, within the voltage range of 2.25 V versus Mg/Mg2+, the V2O3@C exhibited a capacity of 245.1 mAh g−1 when evaluated with magnesium metal in a 0.3 M Mg(TFSI)2 + 0.25 M MgCl2/DME electrolyte. These research findings have important implications for understanding the relationship between the Mg‐ion storage mechanism and reconstructed crystal phase of vanadium oxides as well as the heterointerface reconstruction for the rational design of MIB cathode materials.image

An Ether‐Based Electrolyte Solvation Strategy for Long‐Term Stability and Ultra‐Low Temperature Li‐Metal Batteries

AbstractUnstable solid electrolyte interface (SEI) and dendrite growth hinder the development of rechargeable lithium‐metal batteries (LMBs) at low temperature (≤−20 °C). In this work, regulating the concentration of Li salt increases the proportion of anions in Li+ solvation structure, thereby forming a denser SEI on Li anode. The optimized solvation structure exhibits fast charge transfer kinetics and high‐voltage (dis)charge performance. As a result, Li||Cu cells with modified electrolyte work over 400 h and maintaining an average coulombic efficiency of 98.05%, the Li||LiNi0.8Co0.1Mn0.1O2 cells (N/P = 3) are capable of one hundred stable cycles with a capacity retention of 93.7% even at −40 °C. These findings confirm the effect of ion‐pairing and anion‐derived SEI on the long‐term cycling of LMBs, contributing a promising solution to the development of low‐temperature LMBs.

Benzene-fused porphyrin(2.1.2.1) array: synthesis, structure, and electrocatalytic hydrogen evolution.

The development of efficient molecular catalysts for the electrocatalytic hydrogen evolution reaction (HER) is very necessary and important for fuel cells. In this work, we report a new benzene-fused porphyrin(2.1.2.1) array, BPD, with a unique S-shaped molecular conformation. The electrochemistry of BPD displays multielectron donating and accepting properties owing to the two porphyrin(2.1.2.1) blocks and degenerate molecular orbitals. The electrocatalytic HER activity of BPD is remarkably higher-that is, BPD exhibited lower overpotential, faster HER kinetics, faster charge transfer kinetics, and extended catalytic stability-than that of the porphyrin(2.1.2.1) copper complex monomer.

Tuning ORR selectivity of π-conjugated cobalt corroles from 2e- to 4e-

Efficient oxygen reduction reaction (ORR) is crucial for the performance of fuel cells and other electrochemical devices. Seeking for stable and electrochemically selective 2e- and 4e- ORR electrocatalyst is yet a challenge, making the design extremely important and outmost of interest. In this study, we demonstrate a method to tune ORR selectivity by adjusting the local cobalt density through oligo-/polymerization of π-conjugated cobalt(III) A2B and A3-corroles to linear and two-dimensional matrix structures. These heterogeneous catalysts exhibit remarkable physicochemical properties, fast charge transfer kinetics, electrochemical reversibility, and high durability. Unselective three-electron transfer kinetics with n = 2.5–2.9 in between −0.20 V and +0.40 V vs. RHE are detected with the π-conjugated cobalt(III) A2B- corrole polymers. Highly selective four-electron kinetics with n = 3.7 in between −0.20 V and +0.40 V vs. RHE are detected by employing the cobalt A3-corrole oligomers during the ORR catalysis.

Fast charge transfer kinetics in Sv-ZnIn2S4/Sb2S3 S-scheme heterojunction photocatalyst for enhanced photocatalytic hydrogen evolution

Fast charge transfer kinetics in Sv-ZnIn2S4/Sb2S3 S-scheme heterojunction photocatalyst for enhanced photocatalytic hydrogen evolution

Formation of Iron Phosphide Nanobundles from an Iron Oxyhydroxide Precursor.

Iron phosphide (FeP) nanoparticles have excellent properties such as fast charge transfer kinetics, high electrical conductivity, and high stability, making them a promising catalyst for hydrogen evolution reaction (HER). A challenge to the wide use of iron phosphide nanomaterials for this application is the available synthesis protocols that limit control over the resulting crystalline phase of the product. In this study, we report a method for synthesizing FeP through a solution-based process. Here, we use iron oxyhydroxide (β-FeOOH) as a cost-effective, environmentally friendly, and air-stable source of iron, along with tri-n-octylphosphine (TOP) as the phosphorus source and solvent. FeP is formed in a nanobundle morphology in the solution phase reaction at a temperature of 320 °C. The materials were characterized by pXRD and transmission electron microscopy (TEM). The optimization parameters evaluated to produce the phosphorus-rich FeP phase included the reaction rate, time, amount of TOP, and reaction temperature. Mixtures of Fe2P and FeP phases were obtained at shorter reaction times and slow heating rates (4.5 °C /min), while longer reaction times and faster heating rates (18.8 °C/min) favored the formation of phosphorus-rich FeP. Overall, the reaction lever that consistently yielded FeP as the predominant crystalline phase was a fast heat rate.

Investigation of Electrochemical Stability of ALD Grown Li3PO4 Thin Films and Its Application in High‐Voltage PEO‐based All‐Solid‐State Lithium Batteries

AbstractIn lithium batteries, the interface between electrolytes and electrodes with optimized structural stability and fast charge transfer kinetics plays a pivotal role in achieving overall cycle and rate performance. Introducing a uniform interfacial layer that conducts Li+ ions while insulating electrons, through atomic layer deposition (ALD) of lithium compounds, has shown promise in facilitating lithium ion transport and enhancing interface stability. However, synthesizing lithium compounds with both robust chemical stability and a broad electrochemical window using ALD poses challenges due to the difficulty of obtaining desired products under specific ALD reaction conditions. In this study, this challenge by investigating Li3PO4 is addressed, a compound grown by ALD that exhibits a noteworthy property: the in situ formation of a more stable LiPO3 phase under high applied voltage. The LiPO3 phase possesses an extended theoretical stability window (LiPO3: 2.48‐5.00 V versus Li3PO4: 0.69‐4.21 V), and its emergence substantially enhances the electrochemical performance of all‐solid‐state lithium batteries based on polyethylene oxide (PEO). This work not only presents experimental evidence of the in situ transformation of the interfacial layer but also offers a pragmatic approach to realizing all‐solid‐state lithium batteries with elevated energy density, emphasizing safety and stability considerations.

Multiple Bubble Removal Strategies to Promote Oxygen Evolution Reaction: Mechanistic Understandings from Orientation, Rotation, and Sonication Perspectives.

Bubble coverage of catalytically active sites is one of the well-known bottlenecks to the kinetics of the oxygen evolution reaction (OER). Herein, various bubble removal approaches (electrode orientation, rotating, and sonication) were considered for the OER performance evaluation of a state-of-the-art Ir-based electrocatalyst. Key parameters, such as catalyst mass loss, activity, overpotential, and charge- and mass-transfer mechanisms, were analyzed. First, it was suggested that a suitable orientation of the working electrode facilitates coalescence and sliding bubble effects on the catalyst surface, leading to better electrochemical performance than those of the traditional rotating disk electrode (RDE) configuration. Then, the convection and secondary Bjerknes force were explained as the responsible phenomena in improving the OER activity in the RDE and sonication methods. Finally, simultaneous implementation of the methods enhanced the catalyst mass activity up to 164% and provided fast charge-transfer kinetics and low double-layer capacitance, which eventually led to a 22% reduction in overpotential, while the catalyst loss slightly increased from 1.93 to 3.88%.

Boosting adsorption and dissociation kinetics of magnesium-chloride ion pair via bismuth/indium-based artificial interface

The formation of passivating interphases on Mg-metal anode is impeding the wide employment of rechargeable Mg-metal batteries with less safety and cost concerns. Despite engineering artificial interlayers offers an efficient solution, it still falls short of expectation because of the compromised Mg plating/stripping performances in conventional electrolyte systems. In this work, a unique bismuth/indium-based artificial interface is introduced, which enables an exceptional reversibility (lowest nucleation overpotential of 189 mV than that (583 mV) of pristine Mg anode), high rate capability (a stable charge and discharge operation at 5.0 mA cm−2 without short circuit) and good temperaturetolerance (being cyclable over 10 °C and 50 °C) for the first time. This bismuth/indium-based artificial interface is constructed by facile displacement reactions between Bi(CF3SO3)3/In(CF3SO3)3 and Mg. The dominant interphases, including Bi, In and BiOx species, can be controllably tailored via adjusting the relative ratio and concentration of Bi(CF3SO3)3/In(CF3SO3)3. Theoretical calculation results accompanied by electrochemical experiments indicate that kinetically favorable adsorption and dissociation processes of Mg-Cl ion pair on this interface, affording good magnesiophilic property and fast charge transfer kinetics, are responsible for the improved Mg-metal anode properties.

Excellent ion storage properties of copper-cobalt composite selenide heterostructure in magnesium/lithium hybrid battery

Rechargeable magnesium batteries (RMBs) have emerged as a promising alternative to lithium-ion batteries (LIBs), given their high abundance and desirable safety characteristics. However, the strong polarization of divalent ions has hindered the satisfactory insertion and dissolution of Mg2+ ions in the cathode, thereby limiting the electrochemical performance of the system. To address this issue, magnesium/lithium hybrid batteries (MLHB) have been developed, using both Mg2+ and Li+ ions as carriers to enhance the electrochemical kinetic performance and maintain safety. In this study, a Cu2Se/CoSe heterostructured cathode is designed to extremely promote the electrochemical performance of MLHB. When it is applied to MLHB, the battery exhibites extremely high initial discharge capacity, reversible capacity and cycling stability. The initial discharge capacity obtains 385 mAh g−1 at 100 mA g−1, and a reversible capacity of 140 mAh g−1 is maintained after 200 cycles. The role of the special heterostructures and the effect of pre-lithiation on cathode materials are discussed in detail, on the basis of which a two-step storage mechanism of hybrid ions in Cu2Se/CoSe is proposed. This work lays the foundation for designing and constructing high-capacity, excellent cycle stability cathodes with fast charge-transfer kinetics.

Electrocatalytic and photocatalytic activities of hierarchically structured zinc oxide nanoparticles derived from cellulose paper-precipitated hydrozincite

This study presents a novel method for synthesizing hierarchical porous zinc oxide (ZnO) nanostructures by thermally decomposing green-synthesized hydrozincite. The hydrozincite was prepared at room temperature using zinc acetate dihydrate and calcium carbonate (CaCO3) in cellulose printing papers as the precipitating agent. The resulting ZnO particles exhibit a distinctive flower-like morphology, consisting of porous nanosheets composed of interconnected nanoparticles. The average crystallite size of the hierarchically structured zinc oxide nanoparticles, as determined via X-ray diffraction Rietveld refinement method, was found to be 18.8 nm when calcined at 500 °C. However, with increasing calcination temperature to 600, 700, and 800 °C, the average crystallite size also increased to 24.3, 30.4, and 47.2 nm, respectively. The ZnO synthesized at temperatures of 500 °C, 600 °C, and 700 °C exhibits higher electrocatalytic activity toward the hydrogen evolution reaction (HER) compared to both the ZnO synthesized at 800 °C and commercial ZnO. This enhanced performance can be primarily attributed to the nanosized ZnO particles, which provide a substantial surface area, high accessibility of active sites, and fast charge transfer kinetics. In terms of photocatalytic activity, all the samples show HER improvement under the UV light irradiation, attributed to the generation of photoexcited charge carriers. The ZnO synthesized at 800 °C and the commercial ZnO exhibit greater enhancements in photocatalytic activity compared to the other samples. This implies that larger solid particles with fewer nanopores result in a greater exposed surface area for UV-light absorption. The hierarchically structured ZnO nanoparticles demonstrate promising electrocatalytic and photocatalytic activities, as well as stability, opening up potential applications in various fields, including energy conversion and environmental remediation.