Effective Hydrogen Production Research Articles

Boosting the Production of Hydrogen from an Overall Urea Splitting Reaction Using a Tri-Functional Scandium-Cobalt Electrocatalyst.

The creation of highly efficient and economical electrocatalysts is essential to the massive electrolysis of water to produce clean energy. The ability to use urea reaction of oxidation (UOR) in place of the oxygen/hydrogen evolution process (OER/HER) during water splitting is a significant step toward the production of high-purity hydrogen with less energy usage. Empirical evidence suggests that the UOR process consists of two stages. First, the metal sites undergo an electrochemical pre-oxidation reaction, and then the urea molecules on the high-valence metal sites are chemically oxidized. Here, the use of scandium-doped CoTe supported on carbon nanotubes called Sc@CoTe/CNT is reported and CoTe/CNT as a composite to efficiently promote hydrogen generation from highly durable and active electrocatalysts for the OER/UOR/HER in urea and alkali solutions. Electrochemical impedance spectroscopy indicates that the UOR facilitates charge transfer across the interface. Furthermore, the Sc@CoTe/CNT nanocatalyst has high performance in KOH and KOH-containing urea solutions as demonstrated by the HER, OER, and UOR (215mV, 1.59, and 1.31V, respectively, at 10mA cm-2 in 1m KOH) and CoTe/CNT shows 195 mV, 1.61 and 1.3V, respectively. Consequently, the total urea splitting system achieves 1.29V, whereas the overall water splitting device obtaines 1.49V of Sc@CoTe/CNT and CoTe/CNT shows 1.54, 1.48 V, respectively. This work presents a viable method of combining HER with UOR for maximally effective hydrogen production.

Using MCFC for capturing CO2 from flue gases and delivering to Sabatier reactor for SNG synthesis

In contemporary power generation, enhancing efficiency and mitigating environmental contamination are of paramount importance. The imperative to curtail greenhouse gas emissions stands as a preeminent challenge within this sector. Concurrently, there is a marked surge in the exploitation of renewable energy sources, which, due to their intermittent nature, precipitates the imperative for advanced energy storage solutions. This paper introduces an integrated system designed to address both the reduction of CO2 emissions and the storage of energy. The advocated system integrates a Molten Carbonate Fuel Cell (MCFC), Solid Oxide Electrolysis Cell (SOEC), and a Sabatier reactor. The MCFC is employed for its proficient CO2 capture capabilities at the cathode, exhibiting remarkable efficiency, operational flexibility, and a high CO2 separation quotient. The SOEC is recognized for its effective hydrogen production, leveraging high operational temperatures to augment hydrogen output while diminishing electrical energy consumption through thermal energy substitution. The Sabatier reactor is utilized for catalytic methanation, transforming CO2 into Substitute Natural Gas—a compound predominantly comprising methane and hydrogen with minimal CO2 and water traces. This system facilitates the capture and utilization of over 80% of CO2 from exhaust fumes, achieving an overall energy efficiency of 71%. The system's design and off-design operational parameters were meticulously modeled and analyzed.

Oxygen vacancies promoted hydrogen production from methanol aqueous phase reforming over MgAl−LDHs supported plasmonic Ru nanoparticles catalyst

Catalytic aqueous phase reforming of methanol is a promising process for the sustainable hydrogen production. The search for highly efficient heterogeneous catalyst is a topic of interest. Herein, we report oxygen vacancies enriched MgAl−LDHs supported plasmonic Ru nanoparticles catalyst exhibit excellent photocatalytic performance for efficient hydrogen production at 150 ºC under light irradiation. Characterizations demonstrate abundant oxygen vacancies are introduced into MgAl−LDHs via “memory effect”. The local electron transfer from oxygen vacancies of the MgAl−LDHs to the Ru nanoparticles leading the formation of electron-rich Ru species, which promote the dehydrogenation of methanol under light irradiation. In situ DRIFTS demonstrated a redox mechanism of water-gas shift reaction due to the existence of oxygen vacancies, which resulted a faster hydrogen production rate. This work displays a facile strategy for synthesis of oxygen vacancies rich LDH supported metal nanoparticles catalysts and deep understanding into the pathway and mechanism toward the effective hydrogen production.

Effective hydrogen production and coupling degradation of organics (4-nitrophenol, methylene blue, and Rhodamine B) in wastewater by electrospun PAN@Fe0 composite nanofibers

The pursuit of clean energy generation and environmental preservation is of utmost importance for societal progress. However, couple clean energy production and pollution control is still a difficulty. In this study, a novel electrospun composite mat, with nano zero valent iron (Fe0, nZVI) encapsulated into polyacrylonitrile (PAN) nanofibers was acted as a catalyst. The activation energy (Ea) for the hydrolysis of NaBH4 to produce hydrogen is 22 kJ·mol−1, hydrogen atom utilization efficiency (HGE) of NaBH4 is 60.80%. Three kinds of organic dyes 4-nitrophenol (4-NP), methylene blue (MB), and Rhodamine B (RhB) were served as the model pollutant, to construct NaBH4-organic system for energy production and pollution reduction. The NaBH4-organic system demonstrates a collaborative capability to simultaneously remove organic pollutants and generate hydrogen, with a coupling equilibrium point between the two processes. The hydrogen generation rate (HGR) and HGE increased with the concentration of pollutants increased. The degradation of 4-NP, MB, and RhB followed pseudo-first-order kinetics, with RhB degrading dosage 20 and 44 times higher than 4-NP and MB, respectively. H2 and H· contributed to the organic degradation. nZVI directly participated in the formation H2 and H·. PAN@Fe0 possessed good recyclability and moderate cost. The degradation process adhered to the classical surface reaction controlled Langmuir-Hinshelwood (L-H) model. The integration of synergistic production capacity and pollutant degradation aligns well with the principles of green chemistry and sustainable development. This study demonstrates a novel approach to no precursor loss catalysts preparation, efficient production clean H2, advanced treatment of dye-containing wastewater, carbon neutral operation of sewage treatment plant.

Robust carbon quantum dots supported cobalt oxide composite particles prepared by hydrothermal process for green hydrogen generation via sodium borohydride hydrolysis

Carbon quantum dots (CQDs), a new class of carbon nanostructures with a particle size of 10 nm, exhibit important properties such as easy surface functionalization, low cost, chemical inertness, water solubility and low toxicity. In this study, an effective catalyst was synthesized using cobalt oxide (Co3O4) metal nanoparticles dispersed on CQD support material obtained from sucrose by hydrothermal method (Co3O4-SCQD-HT). The resulting catalyst system was used for effective hydrogen (H2) production from sodium borohydride (NaBH4) hydrolysis. Hydrogen generation rate (HGR) values of 7041, 18,426 and 27,555 mlmin−1gcat−1 were obtained with Co3O4-SCQD catalysts synthesized during the hydrothermal process with water, ethanol and methanol solvents, respectively. The HGR values of the catalysts obtained in ethanol and methanol medium provided an improvement of approximately 2.5 and 4 times, respectively, compared to the catalyst prepared in water medium. The activation energy for NaBH4 hydrolysis by Co3O4-SCQD-HT was 29.92 kJmol−1. Transmission Electron Microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS), nitrogen adsorption/desorption, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Inductively coupled plasma optical emission spectroscopy (ICP-OES) and X-ray photoelectron spectroscopy (XPS) analyses were used for the characterization study. The average particle size for the Co3O4-SCQD-HT nanocomposite is approximately 3.27 nm. The presence of carbon (C), oxygen(O), nitrogen (N) and cobalt (Co) atoms was confirmed by XPS and EDS analysis.

Enhancement of TiO2‐Based Composite With Low Carbon‐Based Component Ratio for Improved Hydrogen Generation via Photocatalytic Water Splitting

AbstractComposite between titanium dioxide (TiO2) and (reduced) graphene oxide (R(GO)) was prepared using a two‐stage solvothermal synthesis with variable R(GO) mass ratios (0.01–5 wt.%). Partial reduction of the precursor solution of GO to RGO took place during the solvothermal synthesis at the elevated pressure and temperature conditions. The structural, morphological, and semiconducting characteristics of the obtained binary composites were determined and their capacity of hydrogen production via photocatalytic water splitting in the presence of triethanolamine (TEOA) as sacrificial agent under the simulated solar light irradiation was tested. Photocatalytic experiments have showed that even low mass ratios of R(GO) component (below 1 wt.%) can have a great influence on the photocatalytic activity and properties of the obtained material. The results showed that even a partial reduction of GO to RGO had a positive impact on the photocatalytic properties of the as‐prepared materials. The composite with 0.05 R(GO) wt.% achieved the highest H2 generation rate of 139 μmol/h/g and maintained high photostability. The incorporation of R(GO) into the TiO2 matrix enhanced efficient charge separation, reduced the energy bandgap (Eg), and thus increased the visible light response (ΔE), leading to more effective hydrogen production.

Complexes Based on Zinc and Cadmium for Visible Light-Driven Hydrogen Production.

Photocatalytic water decomposition using solar energy is one of the most effective hydrogen production technologies. The development of a structurally stable photocatalyst for hydrogen production without cocatalysts and photosensitizers remains a great challenge. In this paper, complex photocatalyst compounds 1 and 2 with different crystal structures were designed and obtained by connecting the 4'-(2,4-disulfophenyl)-4,2':6',4″-terpyridine organic ligands with Zn(Ac)2·2H2O and CdCO3. These products were used for photocatalytic hydrogen production separately, and the hydrogen production rates of compounds 1 and 2 were 0.66 mol·mol-1·h-1 and 0.12 mol·mol-1·h-1, respectively, without the addition of any cocatalysts and photosensitizers, and their charge separation and transfer processes were verified by PL, time-resolved PL, and photocurrent. Compound 1 was tested in 6 cycles over 18 h and showed high stability and reproducibility.

(Invited) Techno-Economics of Photoelectrochemical Water Splitting and Progress in Cost Reduction of High-Efficiency III-V Photoabsorbers

Photoelectrochemical (PEC) water splitting is a potentially promising route to direct solar-driven hydrogen production. Challenging targets for solar-to-hydrogen (STH) efficiency, durability, and semiconductor absorber costs must be realized for this approach to be economically competitive with other hydrogen production pathways. The first part of this talk will focus on the cost and performance metrics that go into techno-economic analysis and their status.Research on PEC hydrogen production at the National Renewable Energy Laboratory (NREL) has focused on III-V semiconductor absorber materials because their tunable bandgaps, high photon conversion efficiencies, and ability to make multi-junction structures that have resulted in the highest STH efficiencies yet demonstrated. However, to achieve the U.S. DOE’s hydrogen production target of $2/kg, in addition to high STH efficiency, the semiconductor absorber synthesis cost must come down 1-2 orders of magnitude from the current metal organic vapor phase epitaxial route. Hydride vapor phase epitaxy (HVPE) is a technique that has the potential to lower tandem III-V synthesis costs. The second part of this talk will describe experimental photoelectrochemical characterizations of HVPE-grown GaInP/GaAs tandem photoelectrodes with 1.85/1.38 eV bandgaps. Their incident photon-to-current efficiency, photocurrent vs. circuit bias, and unbiased chronoamperometry will be presented and discussed. Upon illumination, the HVPE-grown structures were able to drive water electrolysis spontaneously (e.g., without an external bias) at STH efficiencies up to 10%. The durability of III-V photoelectrodes remains an unresolved challenge for cost effective hydrogen production via photoelectrolysis.

Development of three-dimensional iron-doped cobalt phosphides nanorod arrays coupled on nickel substrate for effective hydrogen and oxygen production

To reach practical generation of hydrogen energy from water, it is necessary to synthesize bifunctional effective and durable electrocatalyst towards hydrogen evolution and oxygen evolution reaction (HER and OER). However, the slow kinetics of HER and OER at the cathode and anode is the main bottleneck. Herein, a novel fabrication nanostructure of iron-doped cobalt phosphides nanorod arrays on a conducting nickel foam substrate (Fe-CoxPy NR/NF) is developed with uniform spreading of dopant, high catalytic activity area, rapid efficiency of interfacial charge transfer, and long-time operation by using a facile hydrothermal process and phosphidization. The results displayed that Fe-CoxPy NR/NF exhibited an effective overpotential of 98 mV towards HER and 290 mV towards OER at 10 mA cm−2, which are much lower than those individual CoxPy NR and Fe-CoOH NR materials. In addition, the Fe-CoxPy NR/NF show significant stability in 1.0 M KOH, compared to commercial materials.

Enhancing hydrogen generation through advanced power conditioning in renewable energy integration

Producing hydrogen using renewable energy is a pivotal move towards cleaner and eco-friendlier energy generation, playing a vital role in safeguarding the environment. This method merges power electronic tools with electrolysers, which are key in enhancing hydrogen creation efficiency. Given that electrolysis operate on direct current (DC) voltage, there's a need for DC-DC or AC-DC converters to guarantee the right voltage and current for optimal electrolysis. This study aims to present a power regulation system tailored for hydrogen production powered by renewable resources. This system consists of two main stages: the matrix converter and the 12-pulse diode rectifier. The matrix converter ensures a controlled intake of current from the alternating current (AC) side, leading to a sinusoidal output with limited harmonic disruption. Additionally, it produces an AC voltage with a controlled magnitude and frequency, designed to suit the 12-pulse diode rectifier that follows. This meticulous voltage control is fundamental, granting enhanced operational adaptability and producing a high-quality waveform to support the electrolysis. Finally, the 12-pulse diode rectifier's task is to transform the AC from the matrix converter into a consistent DC voltage, crucial for effective hydrogen production.

Preparation and overall water-splitting performance study of amorphous nickel-copper-phosphide

Hydrogen energy is one of the most important vehicles for energy development in China. One of the effective hydrogen production pathways is overall water-splitting, which is considered as one of the most promising technologies for large-scale hydrogen production. However, its stability, activity, and selectivity still need to be improved. Therefore, in this article, amorphous nickel-copper phosphide was prepared by solvothermal method. Increasing the concentration of ethylene glycol in the solvent makes the solution viscosity increase, which inhibits the nucleation process of the crystal and causes structural distortion, leading to complete amorphization of the nickel-copper phosphide. After the analysis of physical phase and electrocatalytic properties, it can be concluded that the performance of the catalyst is optimal when completely amorphous. When the current density is 10 mA·cm−2, the overpotential of HER and OER are 140.5 and 232.65 mV respectively, and the overall water-splitting overpotential is 1.6404 V. Theoretical calculations indicate that the amorphous phase can optimize the electronic structure, thereby endowing the catalyst with excellent overall water-splitting catalytic activity and stability. This article demonstrates that the formation of an amorphous phase increases the number of active sites on the catalyst, enhancing its catalytic activity, and provides an explanation for the mechanism behind the catalytic performance. This research provides a theoretical foundation for the development of hydrogen production through electrochemical water splitting and expands the design strategies for catalysts.

Unlocking the potential of hematite photoanodes in acidic electrolytes: Boosting performance with ultra‐small IrOx nanoparticles for efficient water splitting

AbstractPhotoelectrochemical (PEC) water splitting offers a promising route for harnessing solar energy to produce clean hydrogen fuel sustainably. A major hurdle has been boosting the performance of photoanode materials within acidic electrolytes—a critical aspect for advancing PEC technology. In response to this challenge, we report a method to augment the efficacy of hematite photoanodes under acidic conditions by anchoring IrOx nanoparticles, replete with hydroxyl groups, onto their surface. A remarkable and steady photocurrent density of 1.71 mA cm−2 at 1.23 V versus RHE was achieved, marking a significant leap in PEC efficiency of hematite in acidic media. The introduction of the IrOx layer notably expanded the electrochemically active surface area for more active sites, fostering improved charge separation and transfer. It also served as an effective hole capture layer, drawing photogenerated holes from hematite to facilitate swift migration to the active sites for the water oxidation process. This advancement has the potential to fully harness the capabilities of hematite photoanodes in acidic environments, thereby smoothing the path toward more effective and sustainable hydrogen production through PEC water splitting.

A dual S-scheme heterojunction SrTiO3/SrCO3/C-doped TiO2 as H2 production photocatalyst and its charge transfer mechanism

Constructing an S-scheme heterojunction is a highly effective approach for enhancing photocatalytic performance. However, the impact of a single S-scheme heterojunction on charge transfer is limited. To overcome this constraint, a dual S-scheme heterojunction, SrTiO3/SrCO3/C-doped TiO2 (referred to as ST/SC/CT), is designed for UV-vis-driven hydrogen production. The mass-normalized and effective surface area-normalized hydrogen production activities of ST/SC/CT are higher than those of ST and CT, respectively. The enhancement in photocatalytic performance is primarily attributed to the improved separation and transfer of photogenerated charge carriers by the dual S-scheme heterojunction. Moreover, C-doping effectively extends the light absorption range from UV to visible and greatly improves the absorption intensity. The heterojunction and charge transfer mechanism are also investigated through microscopy and spectroscopic techniques, as well as density functional theory (DFT) calculations. This work offers valuable insights for the design of novel composites by combining surface modification with heterojunction engineering.

Increasing the capacity of pseudocapacitive WO3 auxiliary electrode for enhanced two-step decoupled acid water electrolysis

Decoupled water electrolysis has all the necessary properties to become an effective hydrogen production tool. Hydrogen evolution is decoupled from oxygen evolution using red-ox mediator electrodes in decoupled electrolysis. Therefore, oxygen and hydrogen are not produced simultaneously or in the same space. This simplifies the design of electrolysers and opens up the possibility of not using membranes and diaphragms for gas separation as conventional electrolysers do. Also, membrane-free technology improves the durability and efficiency of electrolysers. The reduction and oxidation of the red-ox mediator electrode must be reversible. Also, the electrode material should have a high charge capacity and be durable. In this work, we demonstrate WO3 as a red-ox mediator electrode in decoupled water electrolysis with acid electrolyte and investigate the effect of lyophilisation and annealing conditions on WO3 capacity. Indeed, the WO3 electrode can successfully act as a red-ox mediator through intercalation and deintercalation of H+ ions. Lyophilisation increases capacity more than two times than the air-dried sample, 495.55 and 201.41 F/g, respectively. Such high capacities as 837.43 F/g were reached when an inert annealing atmosphere was used. The electrolysis faradaic efficiency of 98–99 % was achieved in all prepared samples, with an energetical efficiency of 34–58 %.

Microwave-assisted sumac based biocatalyst synthesis for effective hydrogen production

Hydrogen (H2), a renewable energy source with a high energy density and a reputation for being environmentally benign, is being lauded for its potential in various future applications. In the present context, the catalytic methanolysis of sodium borohydride (NaBH4) is of considerable importance due to its provision of a pathway for the efficient production of hydrogen gas (H2). The main aim of this research attempt was to assess the viability of utilizing refuse defatted sumac seeds as an unusual precursor in microwave-assisted K2CO3 activation to produce a biocatalyst.The primary objective that motivated the synthesis of the biocatalyst was to facilitate the generation of hydrogen via the catalytic methanolysis of NaBH4. With the aim of developing a biocatalyst characterized by enhanced catalytic performance, we conducted an exhaustive investigation of a wide range of experimental parameters. The activation agent-to-sample ratio (IR), impregnation time, microwave power, and irradiation time were among these parameters.Significantly enhanced in catalytic activity, the biocatalyst produced under particular conditions achieved a peak hydrogen production efficiency of 10,941 mL min− 1 g.cat− 1. In particular, it was determined that the ideal conditions were as follows: 0.5 IR, 24 h of impregnation, 500 W of microwave power, and 10 min of irradiation. This novel strategy not only demonstrates the impressive potential of eco-friendly biocatalysts, but also positions them as a viable alternative material for the sustainable production of hydrogen via NaBH4 methanolysis.Three significant parameters contribute to the value and renewability of this study. The first is that waste is used as the primary material; the second is that the activator is less hazardous than other activators; and the third is that microwave activation is a green chemistry technique.Graphical

A brief review of hydrogen production technologies

As a result of the array of problems arising from the use of fossil fuels, it is necessary to develop and optimize alternative energy technologies. Despite hydrogen being an ideal form of energy, its primary source is still fossil fuels via conventional methods. Therefore, several hydrogen-production resources and techniques have been investigated, providing feasibility for clean and effective hydrogen production. This paper provided a mini-review of hydrogen production technologies, including renewable energy, chemical looping, water electrolysis, photocatalysis, and plasma.

Study on tritium permeation behavior in primary and second circuits of the hydrogen production system by methane steam reforming using HTGR

Hydrogen production by methane steam reforming (MSR) using the process heat from High-temperature gas-cooled reactor (HTGR) is one of the most promising technology for hydrogen production using nuclear energy in the near future. The permeation behavior of tritium produced by the reactor is extremely important when analyzing the safety of this hydrogen production system. There are two methods of connection between a nuclear reactor and a hydrogen production system. One is direct coupling that the steam reformer of the hydrogen production system is directly connected to the first circuit of the nuclear reactor. The other is indirect coupling via an intermediate heat exchanger (IHX) to connect nuclear reactor and hydrogen production system. Hence, this work proposed a model to analyze the difference in tritium permeation between these two coupling ways and to compare the tritium permeation behavior for different IHX alloys at various operating conditions. This model includes tritium's production rate, release fraction, and decay reduction in the system. The results show that the pre-exponential factor of the IHX alloy mainly limits the tritium permeation rate. In addition, the tritium permeation rate increases about two times when the temperature rises from 750 °C to 950 °C at a steady state. Further, the decrease of tritium permeation rate is seen from the calculation results for the system with IHX, e.g., for T = 750 °C, the mean permeation rate of tritium into the product gas is 9.31 × 10−12 mol/s at the whole year for indirect coupling with an IHX, compared to 3.86 × 10−12 mol/s for direct coupling, which reduced 58.54 % (This means that with IHX the permeation rate is lower than the system without IHX). These results will contribute to designing an effective and safe hydrogen production system by MSR using HTGR process heat.

Ce-doping induces rapid electron transfer in a bimetallic phosphide heterostructure to achieve efficient hydrogen production.

Using electrochemical water splitting to generate hydrogen is considered a desirable approach, which is greatly impeded by the sluggish dissociation of H2O and adsorption and desorption of H*. Effective hydrogen production can be achieved by speeding up the chemical process with a suitable electrocatalyst. In this work, we designed and synthesized a rare earth element cerium (Ce) regulated iron-nickel bimetallic phosphide Ce-NiFeP@NF (here NiFeP represents Fe2P/NiP2) nanoarray with nanoflowers. For the hydrogen evolution reaction (HER), Ce-NiFeP@NF only needs an overpotential of 106 mV to provide a current density of 10 mA cm-2, compared to NiFeP@NF (175 mV@10 mA cm-2). This self-supported electrocatalyst Ce-NiFeP@NF with a composite morphology exhibits excellent performance in the HER. Specifically, the introduction of Ce promotes the electron transfer process at the Fe2P/NiP2 heterojunction interface and the Ce-NiFeP@NF nanocomposite structure with nanoflowers has a larger electrochemically active specific surface area, which is more conducive to improving the intrinsic catalytic activity. Also, a dual-electrode alkaline electrolytic cell (Ce-NiFeP@NF functions as both the anode and the cathode) operates with a cell voltage of only 1.56 V to achieve a current density of 10 mA cm-2. The synergistic effect of rare earth element doping and heterojunction engineering can improve the morphology of intrinsic catalysts to achieve more efficient electrochemical water splitting for hydrogen production.

Investigation of the promotion effect of metal oxides on the water-gas shift reaction activity over Pt-MOx/CeO2 catalysts for aqueous phase reforming

Aqueous phase reforming (APR) of methanol is a potential pathway for the effective hydrogen production under relatively mild conditions. The Pt/CeO2 and a series of Pt-MOx/CeO2 (M = Fe, Cr, Mg, Mn) catalysts were prepared by sequential impregnation method and their APR reaction performances were studied. The catalyst properties including valence state of the promoters, the amount of oxygen vacancies, the metal distributions, the adsorption properties of CO and the acidity/basicity of catalysts were characterized and analyzed by XPS, XRD, TEM, CO-TPD, NH3-TPD, CO2-TPD, etc. It was found that the addition of MOx weakened the Pt-CeO2 interaction and promoted the generation of Ptδ+ species with lower valence state, which contribute to the C–H bond cleavage and facilitate methanol conversion. The highest hydrogen production (164.78 mmol) and relatively low CO and CH4 selectivities were obtained over the Pt-MgO/CeO2, while the highest CH4 selectivity was obtained over the Pt-CrOx/CeO2 (2.21%). Over the Pt/CeO2 and Pt-MOx/CeO2 (M = Fe, Cr, Mg, Mn) catalysts, CO2/CH4 ratio correlated well with the catalyst basicity, indicating that the basicity promotes the dissociation adsorption of H2O as well as the water-gas shift (WGS) reaction activity and decreases the methanation activity.

Atomic layer deposited RuO2 with controlled crystallinity and thickness for oxygen evolution reaction catalysis

The effective production of hydrogen as an attractive alternative energy source requires efficient electrocatalysis of the oxygen evolution reaction (OER), the rate-determining step in water splitting. Ruthenium oxide has been investigated as a representative OER catalyst; however, additional research is required for practical applications because of its low stability and varied performance depending on the fabrication method. In this study, RuO2 was prepared via atomic layer deposition (ALD). The crystallinity of the film was controlled by adjusting the ALD growth temperature, and its influence on the OER performance was examined. In addition, ALD cycles were controlled to study the influence of film thickness on the OER performance, allowing for a comparative analysis. The RuO2 film was deposited onto carbon fiber paper (CFP) to enhance its active surface area for the OER. The as-obtained samples were analyzed using various techniques, including X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results showed that the crystalline RuO2 grown at 400 °C performed better catalytic performance than amorphous RuO2 grown at 350 °C, and adjusting the film thickness enhanced the electrochemical performance and stability of the catalyst film.