Hydrogen Production Methods Research Articles

Numerical analysis of catalytic reaction kinetics in methanol steam reformer with variable cross-sectional channel

ABSTRACT Methanol steam reforming (MSR) is a hydrogen production method recognized for its low harmful emissions and high cost-effectiveness. In this study, a three-dimensional numerical model of MSR within channels of variable cross-section. A quantitative relationship between local equilibrium constants and channel structural parameters was established based on the partial pressures of the components. Additionally, the mechanisms by which variable cross-sectional channel structural parameters regulate MSR reaction performance were quantitatively analyzed, considering fluid dynamics, hydrogen production efficiency, and chemical kinetics rates. The results indicate that the kinetic rate of MSR and local equilibrium constants are significantly influenced by the modulation of variable cross-sectional channel structural parameters, with a maximum variation of 50.6%. A positive correlation between methanol conversion rate and the local equilibrium constant of MSR was observed. Utilizing channel structural parameters to enhance MSR led to an 8.75% increase in methanol conversion rate within the same reaction volume. These conclusions may provide theoretical support for regulating volumetric reactions through variable cross-sectional channel structural parameters.

An Overview of Hydrogen Production from Renewable Sources and Its Main Applications

AbstractThere is a misconception that sustainability is only related to greenhouse gas emissions into the atmosphere, and that this is the only risk to which the planet is exposed. Sustainability is a multidimensional concept and must advance simoutaneously on several fronts, such as the urgent need to increase energy, clean water, clean air, food, mobility, health, and poverty reduction. All the problems of these multi‐dimensions are aggravated by the continuous growth of the world population, mainly in economic and socio‐environmental issues. However, the biggest challenge is to increase the supply of clean energy from renewable sources, as all other dimensions of sustainability depend on energy supply and policy decisions. The consumption of fossil fuels has supplied the current energy demand by approximately 87 %. Still, there are predictions of depletion, and the effects caused on the environment by the production of greenhouse gases bring significant economic losses. In this review, we will address the most common methods for hydrogen production, as well as its main technological applications in organic synthesis and for energy generation.

A comprehensive analysis of a compact-sized methanol cracking unit for hydrogen production

Methanol is recognized as source of hydrogen production, making it a suitable fuel for sustainable development. However, hydrogen production methods remain a concern. An experimental setup and a simulation model in Aspen Plus, incorporating an evaporator and cracker, are developed for hydrogen production. The effects of dimensional parameters, including the length and diameter of the cracker, temperature, and pressure in the presence of the catalyst SCST- 403, on hydrogen production and methanol conversion via thermal catalytic cracking have not been discussed yet. The experimental results show that the optimum hydrogen mole fraction exceeds 0.52, and methanol conversion exceeds 60% at a length of 2.83 m, diameter of 4.07 mm, temperature of 500 °C, and pressure of 2.7 MPa. The investigation is extended to redesign the cracker unit using Aspen Plus based on reaction kinetics. Simulations on various dimensions, temperatures, and pressures reveal that, after redesigning, the optimum hydrogen mole fraction exceeds 0.60, and methanol conversion reaches 85% at a length of 4.5 m, diameter of 5.2 mm, temperature of 500 °C, and pressure of 3 MPa.

The feasibility study of alternative fuels production following National Hydrogen Strategy in Slovakia

Hydrogen could be a key driving force for decarbonizing various sectors. This analysis, based on the Slovak National Hydrogen Strategy, evaluates 6 low-emission hydrogen production methods, varying in raw material, technology, and operational conditions. Technologies are assessed using three criteria: levelized cost of energy, carbon footprint, and technology readiness level. Three alternative fuels are analysed: methanol, methane, and sustainable aviation fuel (SAF). Multi-criteria decision analysis evaluates 139 combinations of criteria importance. Proton exchange membrane electrolysis and steam biogas reforming (SBR) emerge as the most advantageous technologies, ranking first in 45 and 32 cases, respectively. Economically, high-temperature electrolysis and SBR are preferred, with a levelized cost (LCOH) of 11.7 €/kg H2 under current conditions. SAF stands out as the best alternative fuel, with the lowest levelized cost of 3.3 €/kg. Reducing Slovakia's electricity price by 80% would make domestic hydrogen production increasingly competitive in Europe by 3.7 times reduction of LCOH.

Hydrogen production from non-potable water resources: A techno-economic investment and operation planning approach

The production of hydrogen through water electrolysis facilitates large-scale energy storage, provides ancillary services, and supports the decarbonization of industries with hard-to-reduce emissions. As renewable energy adoption expands, the demand for these applications is increasing. However, water electrolysis currently faces challenges in cost competitiveness compared to other hydrogen production methods. Additionally, its reliance on potable water sources places additional strain on freshwater reserves. This study addresses these issues by exploring the economically optimal investment and operational strategy for hydrogen production using non-potable water sources. The goal is to maximize net profit through mathematical optimization, utilizing three advanced electrolysis technologies: alkaline electrolysis, proton exchange membrane electrolysis, and solid oxide electrolysis. The study examines three non-potable water sources: seawater, urban wastewater effluent, and rainwater. The model takes into account electricity market values from day-ahead and balancing markets, as well as the market values for hydrogen, oxygen, freshwater, and mixed solid salt. Two scenarios are analysed, reflecting varying levels of uncertainty in electricity price forecasts. Each scenario includes nine case studies, representing various combinations of water sources and electrolysis technologies. The results indicate that alkaline electrolysis and proton exchange membrane electrolysis are financially viable technologies, with potential annual net profits of up to 6.4 and 6.2 million euros, respectively. In contrast, solid oxide electrolysis incurs a negative net profit across all scenarios and is not economically viable under the given conditions. The main revenue sources are hydrogen sales and combined up-balancing and down-balancing services in electricity markets. Participation in the balancing market constitutes a significant portion (35 to 61%) of the total revenue in all cases with positive net profits, making it critical for economic viability. Rainwater is identified as the most cost-effective water source for hydrogen production. However, the costs associated with water treatment and brine management are minimal, contributing only 0.7 to 3.7% to the total cost of hydrogen production. Thus, differences in net profit are primarily attributed to the type of electrolysis technology used.

Assessing hydrogen production potential from carbonate and shale source rocks: A geochemical investigation

The global push towards achieving net-zero carbon dioxide emissions by 2050 shows the urgency of transitioning to a hydrogen-based economy, with clean hydrogen fuel emerging as a fundamental component of future energy consumption. This study explores hydrogen production from geological sources, specifically organic-rich Shale and Carbonate mudrocks, as a significant and sustainable method for natural hydrogen production. Recognizing the critical challenge posed by the interaction of hydrogen with rock-forming minerals and organic matter during production, this research emphasizes the need for a comprehensive understanding of the geochemical composition of these rock materials. To assess the feasibility and implications of utilizing organic-rich source rocks for hydrogen production, we conducted thorough analyses of source rock samples from different formations. The representatives’ samples were subjected to comprehensive analyses including Rock-Eval pyrolysis, X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscope (SEM) examinations, and gas chromatography (GC) analysis of the produced gas. Our results revealed that the high total organic carbon (TOC) samples (average 14.7 %) with Type I and II kerogens yielded substantial hydrogen-rich gases, approximately 44.71 % and 36.02 % for SH-O1 and JOS samples, respectively. JOS produced slightly higher hydrocarbon gases (∼50 %) compared to SH-O1 (∼45 %), along with more H2S (5.78 %), due to higher total sulfur content. In contrast, the SH-C1 sample, characterized by very low TOC (0.27 %), predominantly quartz and muscovite minerals (>78 %), and Type IV kerogen, produced higher CO2 (22.09 %) and minimal hydrogen (1.27 %), highlighting the influence of mineralogical and geochemical composition. This study suggests that hydrocarbon source rocks with high organic matter content hold significant potential for maximizing energy gas recovery (>85 %, including hydrogen and hydrocarbons) through the pyrolysis of their kerogen content. These findings demonstrate the viability of hydrogen gas production from unconventional sources such as organic-rich shales, potentially impacting strategies for sustainable energy production and contributing significantly to global decarbonization efforts.

Enhancing the performance of spinel La-doped CoFe2O4 oxygen carriers for chemical looping hydrogen generation

Chemical-looping hydrogen generation (CLHG) is a clean and efficient method for sustainable hydrogen production. The industrial advancement of the CLHG technology hinges on the development of highly active and selective oxygen carriers (OCs). In this study, the performances of three spinel OCs (ZnFe2O4, CoFe2O4, and NiFe2O4) were investigated in a fixed-bed reactor. CoFe2O4 demonstrated the best reactivity and highest hydrogen yield. In addition, doping CoFe2O4 with varying amounts of La further improved its performance. The highest hydrogen yield (393mL/g) was observed for CoFe2O4 doped with 10 % by mass of La. The characterization results indicated that La not only facilitated the formation of oxygen vacancies but also accelerated lattice oxygen transfer. Furthermore, an optimized La doping level was found to boost the crystallinity of the oxygen carrier, leading to improved cycling performance. The insights gained from probing the performance of La-doped CoFe2O4 OCs are expected to contribute to the development of novel OCs for scaled-up CLHG technology.

Sustainable hydrogen production by integrating solar PV electrolyser and solar evacuated tube collector with hybrid nanoparticles enhanced PCM

The investigation is motivated to analyze the influence of Phase change material (PCM), nano PCMs, and hybrid Nano PCM in sustainable hydrogen production systems. An emerging and highly effective method for hydrogen production involves the use of proton exchange membrane (PEM) technology, which separates water into its constituent parts through electrolysis. Its susceptibility to performance deterioration over time, however, demandsroutine maintenance and component replacement, which negatively impacts operational effectiveness and cost-effectiveness. In this study, the PEM system for electricity and water heating was integrated with the evacuated tube collector and photovoltaic panel to produce hydrogen. Additionally, hybrid Al2O3 and SiO2 nanoparticles with a combined concentration of 0.1 % in equal shares improved the thermal characteristics of PCM in heat exchangers. The research result shows that the heat exchanger of the ETSC circuit with the hybrid nanoparticles enhanced PCM demonstrated improved thermal performance as well as increased hydrogen production. With hybrid nanoparticles enhanced PCM in the heat exchanger, the maximum energy and electrical energy were observed as246.5 kWh and 44.7 kWh, respectively. The ETSC efficiency, electrical efficiency, and PEM electrolyser efficiency reached their highest points at 93.1 %, 15.5 %, and 39.2 %, respectively. Furthermore, hybrid nanoparticle-enhanced PCM produces an average of 25.9 g of hydrogen.

Amorphous P-CoOX Promotes the Formation of Hypervalent Ni Species in NiFe LDHs by Amorphous/Crystalline Interfaces for Excellent Catalytic Performance of Oxygen Evolution Reaction.

Water electrolysis has become an attractive hydrogen production method. Oxygen evolution reaction (OER) is a bottleneck of water splitting as its four-electron transfer procedure presents sluggish reaction kinetics. Designing composite catalysts with high performance for efficient OER still remains a huge challenge. Here, the P-doped cobalt oxide/NiFe layered double hydroxides (P-CoOX/NiFe LDHs) composite catalysts with amorphous/crystalline interfaces are successfully prepared for OER by hydrothermal-electrodeposition combined method. The results of electrochemical characterizations, operando Raman spectra, and DFT theoretical calculations have demonstrated the electrons in the P-CoOX/NiFe LDHs heterointerfaces are easily transferred from Ni2+ to Co3+ because that the amorphous configuration of P-CoOX can well induce Ni-O-Co orbital coupling. The electron transfer of Ni2+ to the surrounding Fe3+ and Co3+ will lead to the unoccupied eg orbitals of Ni3+ that can promote water dissociation and accelerate *OOH migration to improve OER catalytic performance. The optimized P-CoOX/NiFe LDHs exhibit superior catalytic performance for OER with a very low overpotential of 265mV at 300mA cm-2 and excellent long-term stability of 500h with almost no attenuation at 100mA cm-2. This work will provide a new method to design high-performance NiFe LDHs-based catalysts for OER.

Sorption-enhanced ethanol steam reforming coupled with in-situ CO2 capture and conversion

The impacts of climate change and the issue of greenhouse gas emissions have sparked research into renewable energy alternatives to fossil fuels. Hydrogen has gained attention as a clean, renewable and environmentally friendly energy source. Enhanced-ethanol steam reforming has been proposed as a promising method for blue hydrogen production, addressing greenhouse gas emission issues. The use of catalysts enhances the adsorption of ethanol and water molecules on the surface, promoting the reaction rate. This study systematically explored the effects of different Fe loading and CaO addition ratios on the ethanol steam reforming and CO2 conversion processes to optimize catalyst performance. The experimental results showed that Fe/SiC catalysts effectively promoted the conversion of ethanol and generated high-purity hydrogen, exhibiting excellent catalytic activity. Specifically, a catalyst with 10 % Fe loading and mixed with 0.3g CaO significantly increased the hydrogen yield to 64.4 mmol/g, which was 2.88 times higher than that without the catalyst.

Low-emission hydrogen production from gasification of Australian coals – Process simulation and technoeconomic assessment

Although renewable energy-based technologies such as water electrolysis and biomass gasification for hydrogen production are cleaner than fossil energy-based routes, there are still prevailing challenges associated with the high cost and operational challenges in the scale-up of those technologies in the short term. Considering the abundance of coal as a current primary source of energy in Australia, the use of coal to produce hydrogen is not only in line with Australia's resource endowment but is also expected to become a supplement to the other hydrogen production pathways during the global energy transition period. This paper presents a comprehensive techno-economic assessment of low-emission hydrogen production from Australian coal gasification integrated with carbon capture and storage (CCS). The study explores four cases of hydrogen production, comparing Australian brown coal (Victorian brown coal) and black coal (Queensland black coal) gasification. Variations in gasifiers, gasification agents, and associated operating conditions contribute to differences in energy efficiency, costs, and CO2 emissions among the cases. The findings reveal a levelized cost of hydrogen from coal gasification ranging between A$4.12–4.90 per kg of hydrogen. Notably, entrained flow gasification of Victorian brown coal in a mixture of oxygen and steam environment demonstrates advantages under the current market conditions. However, less mature technologies like dual fluidized bed gasifiers could emerge as viable alternatives if deployed on a commercial scale. The study also addresses direct carbon emissions from the process, indicating a CO2 emission intensity range of 16.3–20.9 kg CO2/kg H2 without CCS and 0.1–1.1 kg CO2/kg H2 with CCS for the four cases. These insights contribute valuable information for decision-making in the pursuit of sustainable and economically feasible hydrogen production methods during the ongoing energy transition.

Exergetic efficiency and CO2 intensity of hydrogen supply chain including underground storage

Hydrogen plays a crucial role in the transition to low-carbon energy systems, especially when integrated into energy storage applications. In this study, the concept of exergy-return on exergy-investment (ERoEI) is applied to investigate the exergetic efficiency (defined as the ratio of useful exergy output to invested exergy input) and CO2 equivalent intensity of the hydrogen supply chain, with a specific focus on the underground hydrogen storage process. Our findings reveal that the overall exergetic efficiency of the electricity-to-hydrogen-to-electricity conversion process can reach up to 25 %. Among the hydrogen production methods, green hydrogen, produced via electrolysis powered by renewable energy, exhibits the lowest CO2 equivalent intensity. Blue hydrogen, produced from natural gas with carbon capture, can significantly reduce the carbon footprint of electricity generation, though this advantage comes at the expense of decreased exergetic efficiency. Analysis further indicates that the exergetic efficiency of underground storage components ranges from 72 % to 92 %. A substantial fraction of the exergy is lost during compression and injection of the stored hydrogen. Nevertheless, the subsurface operations contribute a minimal CO2 emission, between 1.46–4.56 grams of equivalent CO2 per megajoule (gr-CO2eq/MJ) when powered by low-carbon energy sources. Furthermore, it is found that hydrogen loss in the reservoir, along with methane and hydrogen leak during surface operations, notably affects the overall efficiency of the storage process.

Hydrogen production from photocatalytic water splitting in the hBNC/MoS2 heterojunction: First-principles calculations

Photocatalytic water splitting for hydrogen production is a kind of hydrogen production method with less pollution and low cost. We designed the hBNC/MoS2 heterojunction as a photocatalyst for hydrogen production. This investigation is based on the first-principles. The results show that hBNC/MoS2 heterojunction has type-II band alignment. Moreover, the built-in electric field makes the photo-generated carries transfer along Z-scheme path. The hBNC/MoS2 has suitable band edge positions for hydrogen evolution reaction and oxidation evolution reaction. The reduction reaction overpotential is 2.27 eV (χH2 = 2.27 eV) in hBNC/MoS2. Meanwhile, the visible light absorption is improved in this heterojunction compared with the monolayer hBNC and MoS2. In addition, the Gibbs free energy calculation confirmed that the HER under the light irradiation in hBNC/MoS2 is an exothermic and spontaneous process. This investigation indicates that the hBNC/MoS2 heterojunction has potential application prospect in photocatalytic hydrogen production.

Comparative analysis of methane and natural gas pyrolysis for low-GHG hydrogen production

Methane pyrolysis is emerging as an attractive clean hydrogen production method. As its commercialization proceeds, the pyrolysis of natural gas (NG) becomes pertinent. In this work, the decomposition of pure methane and a realistic NG mixture are compared experimentally and numerically. Methane and NG pyrolysis are performed between 600 and 1200 °C over a fluidized bed of carbon particles heated by microwaves. Experimentally, no conclusive difference is observed in methane conversion between methane and NG pyrolysis. Numerically, the methane conversion rate is 8.5% higher for NG at 950 °C. The difference diminishes past 950 °C, becoming 0 past 1050 °C. The simulations showed that the enhanced methane decomposition in NG pyrolysis is due to an attack on methane by radicals generated during ethane and propane decomposition. The CO2 in our NG mixture decomposes into CO. This work validates the longstanding use of methane pyrolysis as a surrogate for NG pyrolysis.

AlGaAs as an Alternative Solar Water Splitting Material: Insights into Performance, Stability, and Future Directions.

This study offers an in-depth examination of aluminum gallium arsenide (AlGaAs) as a high-performance and durable material for photoelectrochemical water splitting, a key method of cost-effective renewable hydrogen production. Purpose-designed pin-AlGaAs photocathodes are demonstrated to yield a remarkable photocurrent density of over 15 mA/cm2 and an impressive onset potential of 1.11 V vs RHE. These results significantly outperform those achieved with other materials, marking a considerable advancement in the field. Moreover, this work addresses the long-standing issue of AlGaAs corrosion in an aqueous electrolyte. An innovative approach using a 60 nm TiO2 protection layer is introduced, providing substantial corrosion resistance in acidic environments and thereby enhancing material durability. This research also provides valuable insights into the role of passivation layers on charge transfer. It was found that an n-GaAs passivation layer further enhances the onset potential, whereas an n-InGaP layer contributes to a decline in the overall performance. These findings pave the way for new applications of AlGaAs in solar water splitting technology, offering a promising pathway toward the development of efficient AlGaAs/Si tandem water splitting devices.

An Efficient and Stable MXene-Immobilized, Cobalt-Based Catalyst for Hydrogen Evolution Reaction

Hydrogen (H2) is considered to be the best carbon-free energy carrier that can replace fossil fuels because of its high energy density and the advantages of not producing greenhouse gases and air pollutants. As a green and sustainable method for hydrogen production, the electrochemical hydrogen evolution reaction (HER) has received widespread attention. Currently, it is a great challenge to prepare economically stable electrocatalysts for the HER using non-precious metals. In this study, a Co/Co3O4/Ti3C2Tx catalyst was synthesized by supporting Co/Co3O4 with Ti3C2Tx. The results show that Co/Co3O4/Ti3C2Tx has excellent HER activity and durability in 1 mol L−1 KOH, and the overpotential and Tafel slope at 10 mA·cm−2 were 87 mV and 61.90 mV dec−1, respectively. The excellent HER activity and stability of Co/Co3O4/Ti3C2Tx can be explained as follows: Ti3C2Tx provides a stable skeleton and a large number of attachment sites for Co/Co3O4, thus exposing more active sites; the unique two-dimensional structure of Ti3C2Tx provides an efficient conductive network for rapid electron transfer between the electrolyte and the catalyst during electrocatalysis; Co3O4 makes the Co/Co3O4/Ti3C2Tx catalyst more hydrophilic, which can accelerate the release rate of bubbles; Co/Co3O4 can accelerate the adsorption and deionization of H2O to synthesize H2. This study provides a new approach for the design and preparation of low-cost and high-performance HER catalysts.

Cu-doped ZnCdS-based photocatalyst for efficient photocatalytic hydrogen production by photothermal assistance

In solar energy utilization, photocatalytic hydrogen production has been widely researched. To address issues such as low efficiency of photocatalysts, Cu-doped Zn0.5Cd0.5S composite photocatalysts were prepared using a hydrothermal method for photocatalytic hydrogen production. The Cu/Zn0.5Cd0.5S photocatalyst was characterized using XRD, XPS, SEM, TEM, UV–vis-DRS, fluorescence spectrophotometer, and electrochemical workstation. The results indicate that Cu doping alters the crystal and band structures of Zn0.5Cd0.5S. Hydrogen production experiments were conducted under xenon lamp irradiation, and at 45 °C, the highest hydrogen production rate was 2.72 and 1.63 times that of single Zn0.5Cd0.5S and Cu-doped Zn0.5Cd0.5S at room temperature (25 °C), respectively. Cu doping imparted a photothermal effect to the photocatalytic hydrogen production experiment, enhancing its efficiency.Cu doping captured electrons by replacing some Zn, constructing an internal electric field, forming defect energy levels, which hindered electron-hole recombination. Additionally, Cu ions acted as a plasma, inducing a plasma effect during hydrogen production, accelerating the rate of solar energy conversion to thermal energy, thus improving hydrogen production efficiency. This research not only provides a photocatalyst for photocatalytic hydrogen production but also utilizes it for photothermal synergistic catalysis.

Integrated scheme analysis and thermodynamic performance study of advanced nuclear-driven hydrogen-electricity co-production systems with iodine-sulfur cycle and combined cycle

A promising method for massive clean hydrogen production is the Very High Temperature Reactor (VHTR)-driven Nuclear Hydrogen Production (NHP) system using the Iodine–Sulfur (IS) cycle. Research on integrated scheme and thermodynamic performance of the VHTR-driven NHP system using the IS cycle has, however, received little attention up to this point, particularly when the combined cycle is employed as the power generation cycle. In order to bridge this research gap, this work proposed and studied two distinct VHTR-driven hydrogen-electricity co-production systems with the IS cycle and combined cycle: the independent operating system and the coupled operating system. Thermodynamics was used to model these two systems, and system thermodynamic performance was examined under the baseline operating conditions. A parametric study was further conducted on how two important operating parameters affected system thermodynamic performance. The primary findings indicated that the coupled operating system outperformed the independent operating system in terms of thermodynamic performance. Additionally, both the independent and coupled operating systems could produce hydrogen at the same rate of 289.8 mol/s, with net electrical power outputs of 61.07 MW and 102.7 MW, respectively, under the baseline operating conditions. Furthermore, it was discovered that a rise in the mass flow ratio for both operating systems would result in a notable reduction in system efficiency.

Green Hydrogen in Focus: A Review of Production Technologies, Policy Impact, and Market Developments

This paper navigates the critical role of hydrogen in catalyzing a sustainable energy transformation. This review delves into hydrogen production methodologies, spotlighting green and blue hydrogen as pivotal for future energy systems because of their potential to significantly reduce greenhouse gas emissions. Through a comprehensive literature review and a bibliometric analysis, this study underscores the importance of technological advancements, policy support, and market incentives in promoting hydrogen as a key energy vector. It also explores the necessity of expanding renewable energy sources and international cooperation to secure a sustainable, low-carbon future. The analysis highlights the importance of scalable and cost-effective hydrogen production methods, such as solar-thermochemical and photo-electrochemical processes, and addresses the challenges posed by resource availability and geopolitical factors in establishing a hydrogen economy. This paper serves as a guide for policy and innovation toward achieving global sustainability goals, illustrating the essential role of hydrogen in the energy transition.

Electrodeposited manganese carbonate as an electrocatalyst for hydrogen evolution reaction in acidic medium

The electrolysis of water is the key method for hydrogen production but the high overpotential necessitates electrocatalysts. Traditionally, Pt is used, but it is scarce and costly. Herein, MnCO3 is unveiled as an electrocatalyst for the production of hydrogen. MnCO3 is electrodeposited onto pencil graphite by chronoamperometric method and confirmed by XRD and vibrational spectroscopic studies. MnCO3 electrodeposited for 15 min at 2 V demonstrates a good HER activity (overpotential of 123 mV to reach 10 mA cm−2) in 0.5 M H2SO4 with a Tafel slope of 79 mV dec−1. In addition, MnCO3 exhibited good stability during continuous operation (over 3000 cycles and 14 h). Though MnCO3 requires higher overpotential than the benchmark catalyst (Pt/C) to reach 10 mA cm−2, it outperforms Pt/C at higher current density (≥75 mA cm−2) demonstrating that MnCO3 could be used as an electrocatalyst to produce H2 at a high rate from acidic medium.