Enhanced Hydrogen Production Research Articles

Enhancing hydrogen production prediction from biomass gasification via data augmentation and explainable AI: A comparative analysis

Hydrogen production for clean energy is gaining a foothold, notably through the gasification of biomass. Machine learning aids in its accurate production predictions, yet its opaque nature limits explanation. This study looked into machine learning models' transparency and evaluated the impact of data augmentation on hydrogen production prediction accuracy using a publicly available numerical dataset. Fifteen (15) machine learning regression models including linear and tree-based were evaluated leading to the introduction of a hybrid model. The proposed hybrid model is based on ensemble and averaging techniques in mathematics. The deployed model's prediction was evaluated using the Mean Absolute Error (MAE), the Mean Square Error (MSE), the Root Mean Squared Error (RMSE), the Root Mean Squared Log Error (RMSLE), and R-squared (R2) based on K-Fold cross-validation. Furthermore, the effect of the grid search, random search, and Bayesian optimization techniques for model hyperparameter optimization were carried out. The evaluated models demonstrate superior predictions and explore data augmentation's potential in refining machine learning accuracy with the proposed hybrid model recording an MAE of 2.187, MSE of 9.788, RMSE of 3.129, R2 of 0.250, MSLE of 0.005, and RMSLE of 0.070 against the original data result of MAE of 2.665, MSE of 11.877, RMSE of 3.446, R2 of 0.112, MSLE of 0.006 and RMSLE of 0.076. However, when the proposed model hyperparameter training setting was optimized, the yielded result improved further with an MAE of 0.044, MSE of 0.040, RMSE of 0.215, R2 of 0.996, MSLE of 0.000 and RMSLE of 0.005. By unraveling the inner workings of black box models using the SHAP, LIME, and ELI-5 interpretable AI models, this study advances hydrogen production prediction using biomass gasification. Insights gained in this study foster the development of more transparent and effective models, aiming for the widespread adoption of sustainable hydrogen energy.

When less is more: Enhancement of green hydrogen production and efficiency by using electrodes with ultra-low platinum loadings

Sulfur dioxide depolarized electrolysis (SDE) is a promising technology for cost-effective green hydrogen production that can be used for the storage of intermittent renewable energies used to power the electrolyzer. The obtained hydrogen can be stored and used as a source for producing electricity in a fuel cell. However, high platinum loadings (around 2 mgPt cm−2) in the anode and cathode electrodes significantly contribute to the overall cost of the electrolyzer. This study aimed to optimize both electrodes using the electrospray technique for the deposition of ultra-low Pt loadings. The electrodes achieved a total platinum loading as low as 0.4 mgPt cm−2 (0.3 mgPt cm−2 for the anode and 0.1 mgPt cm−2 for the cathode), an 80 % reduction compared to common platinum loadings. This reduction not only increased the hydrogen production rate (18 mL min−1 with optimized electrodes vs. 4.7 mL min−1 with non-optimized electrodes) but also decreased the production of hydrogen sulfide in the cathode, resulting in a hydrogen stream with higher purity. Overall, this study demonstrates the potential of electrospray for achieving low platinum loadings and improving the efficiency of SDE for green hydrogen production.

Hierarchical Heterometallic Sulfur/Selenide Electrocatalysts Derived from Polyoxometalate for Enhanced Hydrogen Production Performance

Hierarchical Heterometallic Sulfur/Selenide Electrocatalysts Derived from Polyoxometalate for Enhanced Hydrogen Production Performance

Metal doped TiO2 decorated carbon nanostructured materials as an emerging photocatalysts for solar fuels production

The concept of photocatalytic CO2 and H2O conversion to solar fuels and value-added products provides simultaneous solution for increased energy demands and environmental problems. However, the lack of efficient photocatalysts restrains the large-scale development of photocatalytic technology. In the present study, noble (Pt and Au) and transition metal (Ni) doped nanoflakes assembled on TiO2@carbon microrods with high surface area and rutile crystal structure is prepared via fast, versatile solvothermal method. The photocatalytic performance of the prepared nanocomposites was evaluated in two photocatalytic systems: CO2 reduction and hydrogen production via photoreforming. Pt-doped catalyst showed enhanced hydrogen production efficiency and increased CH4 selectivity, while Ni-doped catalyst exhibited remarkable CO2 reduction activity with higher selectivity towards CO. The mechanism of Pt-promoted CH4 formation and Ni- and Au-promoted CO formation was thoroughly discussed regarding kinetic and thermodynamic parameters.

Enhancing bioelectrochemical hydrogen production from industrial wastewater using Ni-foam cathodes in a microbial electrolysis cell pilot plant

Microbial electrolysis cells (MECs) have garnered significant attention as a promising solution for industrial wastewater treatment, enabling the simultaneous degradation of organic compounds and biohydrogen production. Developing efficient and cost-effective cathodes to drive the hydrogen evolution reaction is central to the success of MECs as a sustainable technology. While numerous lab-scale experiments have been conducted to investigate different cathode materials, the transition to pilot-scale applications remains limited, leaving the actual performance of these scaled-up cathodes largely unknown. In this study, nickel-foam and stainless-steel wool cathodes were employed as catalysts to critically assess hydrogen production in a 150 L MEC pilot plant treating sugar-based industrial wastewater. Continuous hydrogen production was achieved in the reactor for more than 80 days, with a maximum COD removal efficiency of 40 %. Nickel-foam cathodes significantly enhanced hydrogen production and energy efficiency at non-limiting substrate concentration, yielding the maximum hydrogen production ever reported at pilot-scale (19.07 ± 0.46 L H2 m−2 d−1 and 0.21 ± 0.01 m3 m−3 d−1). This is a 3.0-fold improve in hydrogen production compared to the previous stainless-steel wool cathode. On the other hand, the higher price of Ni-foam compared to stainless-steel should also be considered, which may constrain its use in real applications. By carefully analysing the energy balance of the system, this study demonstrates that MECs have the potential to be net energy producers, in addition to effectively oxidize organic matter in wastewater. While higher applied potentials led to increased energy requirements, they also resulted in enhanced hydrogen production. For our system, a conservative applied potential range from 0.9 to 1.0 V was found to be optimal. Finally, the microbial community established on the anode was found to be a syntrophic consortium of exoelectrogenic and fermentative bacteria, predominantly Geobacter and Bacteroides, which appeared to be well-suited to transform complex organic matter into hydrogen.

Graphitic carbon nitride nanosheet and ferroelectric PbTiO3 nanoplates S-scheme heterostructure for enhancing hydrogen production and textile dye degradation

Graphitic carbon nitride (g-C3N4) is a reliable photocatalyst that can be activated by visible light. However, its photocatalytic efficiencies are hindered by the rapid recombination of charge carriers on its surface. A hybrid photocatalyst consisting of a ferroelectric PbTiO3 nanoplate/g-C3N4 S-scheme heterojunction was synthesized using an ultrasonic-assisted hydrothermal method, to overcome the aforementioned limitation. The PbTiO3 nanoplates incorporated into the g-C3N4 matrix created a strong electric field, resulting in superior photocatalytic activities. This improvement can be attributed to the efficient separation of the photogenerated charge carriers. The hybrid photocatalyst (10PTCN) exhibits an impressive H2 evolution rate (1587.82 µmol.g−1.h−1) under simulated solar irradiation. The hybrid photocatalysts demonstrated 99.40 % methylene blue (30 mg·L−1) in 90 min under simulated solar irradiation with remarkable reusability. This work contributes to enhancing the understanding of utilizing ferroelectric 2D nanoplates to develop efficient charge transfer schemes for improved photocatalysts.

External Electrons Directly Stimulate Escherichia coli for Enhancing Biological Hydrogen Production.

External electric field has the potential to influence metabolic processes such as biological hydrogen production in microorganisms. Based on this concept, we designed and constructed an electroactive hybrid system for microbial biohydrogen production under an electric field comprised of polydopamine (PDA)-modified Escherichia coli (E. coli) and Ni foam (NF). In this system, electrons generated from NF directly migrate into E. coli cells to promote highly efficient biocatalytic hydrogen production. Compared to that generated in the absence of electric field stimulation, biohydrogen production by the PDA-modified E. coli-based system is significantly enhanced. This investigation has demonstrated the mechanism for electron transfer in a biohybrid system and gives insight into precise basis for the enhancement of hydrogen production by using the multifield coupling technology.

Enhancing hydrogen production capability from urine-containing sewage through optimization of urea oxidation pathways

The electrochemical urea oxidation reaction (UOR) represents a promising route to sustainable hydrogen production and reuse of urea-containing sewage. However, the efficiency of UOR is hindered by the dehydrogenation of intermediate *CONH2NH and the conversion of toxic intermediate the *CO. Herein, we report a robust strategy to elevate UOR performance by introducing iron (Fe) atoms into the Ni3S2@NiSe2 heterojunctions (denoted Fe-Ni3S2@NiSe2). The Fe-Ni3S2@NiSe2 exhibits remarkable selectivity and electrocatalytic activity towards UOR, attributed to its reconstruction into Fe-NiOOH species during UOR process, as confirmed by in-situ Raman technology. Utilizing Fe-Ni3S2@NiSe2 as both the cathode and anode in a single-chamber electrolytic cell, the hydrogen production rate reaches 588.4 μmol h−1 in simulated urea-containing sewage and 432.1 μmol h−1 in actual human urine, respectively. Notably, in both scenarios, no oxygen product is detected, and the hydrogen production efficiency surpasses that of traditional water splitting by 5.8-fold and 4.3-fold, respectively. In-situ infrared spectroscopy study reveals that the UOR process involves the cleavage of C-N bond and the generation of CO2. Density functional theory calculations further signifies that the incorporation of Fe facilitates the dehydrogenation of *CONH2NH intermediates, strengthens the d-p hybridization, and weakens O-H bonds, thereby resulting in reduced energy barriers for UOR. Our strategy holds promise for efficient hydrogen production from sewage via UOR, offering potential implications for wastewater treatment and clean energy generation.

Investigations to intensified hydrogen production via sorption enhanced water gas shift reaction

Sorption enhanced water gas shift (SEWGS) reaction for the equilibrium enhanced hydrogen production is investigated using lithium orthosilicate (Li4SiO4) sorbents mixed with 1 wt% Pt/Al2O3 catalysts. The Li4SiO4 sorbents, synthesized using novel surfactant-mediated method, are characterized by ultra-fast CO2 capture rates with CO2 absorption capacity in the range of 319–333 mgCO2·g−s1. The thermogravimetric analysis results show ∼ 26 wt% of the carbonation sites are participating in the fast CO2 absorption (∼ 298 mgCO2·g−s1·min−1). The use of these sorbents with 1 wt% Pt/Al2O3 catalysts in the water gas shift reaction show a 103% increase in the hydrogen yield compared to the equilibrium concentration at 600◦C. The Li4SiO4 sorbent-catalyst combination show a shift in the equilibrium by preventing the reverse reaction in the temperature range of 600–650◦C. The SEWGS experiments show that the CO2 absorption capacities, and consequently the hydrogen yields, are affected by the diffusional resistance across Li2CO3 and Li2SiO3 product domains in the sorbent. The Li4SiO4 conversion rates during the SEWGS reaction are measured by sampling at different points in the SEWGS reaction and subsequent Rietveld analysis of the XRD patterns. The XRD results suggest the decrease in CO2 absorption rates as a result of the formation of additional Li2CO3 and Li2SiO3 fractions with decreasing Li4SiO4 phase in this nano-structured composite.

Thermophilic self-fermentation of chicken manure for enhanced soluble metabolite products and bio‑hydrogen production

Treating chicken manure (CM) through anaerobic digestion encounters a hurdle due to its high nitrogen content, leading to volatile fatty acid accumulation and methanogenesis disruption. To overcome this, redirecting the process to yield soluble metabolite products (SMPs) and hydrogen is proposed. Mesophilic (30 °C) and thermophilic (55 °C) acidogenesis were employed, utilizing self-fermentation and sludge augmentation at various total solids (TS) concentrations ranging from 2.5 % to 20 %. SMP production showed direct proportionality to TS concentration. Optimal conditions were observed in thermophilic self-fermentation at 15 % TS, yielding 0.20 ± 0.01 g SMPs/g volatile solid. Moreover, the mass balance analysis revealed 46.68 g of SMPs, equivalent to 53.82 g of soluble chemical oxygen demand (SCOD) solubilized in the total SCOD of 63.56 g in the effluent. Although thermophilic bioaugmentation enhanced hydrogen production, its impact on SMPs was insignificant. This study underscores the potential of CM self-fermentation, highlighting its organic matter and microorganism-rich characteristics.

Shewanella oneidensis-based artificial conductive micro-niche for hydrogen augmentation

The synergetic integration of living microorganisms and nonliving matrices into a new artificial micro-ecological system is a crucial challenge in bio-manufacturing especially towards the development of sustainable energy technology. Here we develop a way of creating a Shewanella oneidensis based conductive micro-niche to boost hydrogen production by integrating graphene, polydopamine and alginate. We reveal that both the respiratory metabolism induces localized hypoxic conditions inside the micro-niche and the wired-up extracellular electron reverses transfer pathway from the outer environment to the periplasmic hydrogenases, contributing to the enhanced hydrogen production rate which is about 12.7 folds enhancement compared with that of the free Shewanella oneidensis in solution. Significantly, the whole assembly process shows good biocompatibility, ensuring that the Shewanella oneidensis inside the micro-niche could maintain hydrogen production for 30 days. Overall, it is anticipated the hybrid integration of microorganisms and abiotic material will provide an effective strategy to modulate green biomanufacturer as well as enhance biological hydrogen production.

Comparative study of interfacial charge transfer at the junction between CuInS2:In2S3/g-C3N4 photocatalysts for sacrificial hydrogen evolution activity

The quest for sustainable and efficient renewable energy sources has escalated in recent years, with photocatalytic hydrogen production gaining prominence due to its potential to harness solar energy for clean fuel generation. In this study, we design 2D/2D heterostructure CuInS2:In2S3/g-C3N4 nanosheets utilizing electrostatic interaction for hydrogen evolution reaction under visible light irradiation. Integrating CuInS2:In2S3 and g-C3N4 layers to form an interfacial 2D:2D heterostructure results in a broad light absorption range, effective charge separation, and excellent stability. The heterostructure ensures efficient interfacial charge transfer pathways, mitigating electron-hole recombination and promoting hydrogen evolution. The hybrid nanosheets prepared with the hydrothermal method exhibited ∼40-fold synergistic enhancement in hydrogen production and long-term stability. The synergistic boost in activity resulted from the formation of S-scheme heterojunctions (CuInS2/g-C3N4 and CuInS2/In2S3) within hybrid nanosheets.

Salt and heat stress enhances hydrogen production in cyanobacteria.

Cyanobacteria are among the most suitable organisms for the capture of excessive amounts of CO2 and can be grown in extreme environments. In our research we use the single-celled freshwater cyanobacteria Synechococcus elongatus PCC7942 PAMCOD strain and Synechocystis sp. PCC6714 for the production of carbohydrates and hydrogen. PAMCOD strain and Synechocystis sp. PCC6714 synthesize sucrose when exposed to salinity stress, as their main compatible osmolyte. We examined the cell proliferation rate and the sucrose accumulation in those two different strains of cyanobacteria under salt (0.4M NaCl) and heat stress (35 0C) conditions. The intracellular sucrose (mol sucrose content per Chl a) was found to increase by 50% and 108% in PAMCOD strain and Synechocystis sp. PCC6714 cells, respectively. As previously reported, PAMCOD strain has the ability to produce hydrogen through the process of dark anaerobic fermentation (Vayenos D, Romanos GE, Papageorgiou GC, Stamatakis K (2020) Photosynth Res 146, 235-245). In the present study, we demonstrate that Synechocystis sp. PCC6714 has also this ability. We further examined the optimal conditions during the dark fermentation of PAMCOD and Synechocystis sp. PCC6714 regarding H2 formation, increasing the PAMCOD H2 productivity from 2 nmol H2 h- 1 mol Chl a- 1 to 23 nmol H2 h- 1 mol Chl a- 1. Moreover, after the dark fermentation, the cells demonstrated proliferation in both double BG-11 and BG-11 medium enriched in NaNO3, thus showing the sustainability of the procedure.

A novel microbial community restructuring strategy for enhanced hydrogen production using multiple pretreatments and CSTR operation

To achieve rapid enrichment of the targeted hydrogen-producing bacterial population and reconstruction of the microbial community in the biological hydrogen-producing reactor, the activated sludge underwent multiple pretreatments using micro-aeration, alkaline treatment, and heat treatment. The activated sludge obtained from the multiple pretreatments was inoculated into the continuous stirred tank reactor (CSTR) for continuous operations. The community structure alteration and hydrogen-producing capability of the activated sludge were analyzed throughout the operation of the reactor. We found that the primary phyla in the activated sludge population shifted to Proteobacteria, Firmicutes, and Bacteroidetes, which collectively accounted for 96.69% after undergoing several pretreatments. This suggests that the multiple pretreatments facilitated in achieving the selective enrichment of the fermentation hydrogen-producing microorganisms in the activated sludge. The CSTR start-up and continuous operation of the biological hydrogen production reactor resulted in the reactor entering a highly efficient hydrogen production stage at influent COD concentrations of 4000 mg/L and 5000 mg/L, with the highest hydrogen production rate reaching 8.19 L/d and 9.33 L/d, respectively. The main genus present during the efficient hydrogen production stage in the reactor was Ethanoligenens, accounting for up to 33% of the total population. Ethanoligenens exhibited autoaggregation capabilities and a superior capacity for hydrogen production, leading to its prevalence in the reactor and contribution to efficient hydrogen production. During high-efficiency hydrogen production, flora associated with hydrogen production exhibited up to 46.95% total relative abundance. In addition, redundancy analysis (RDA) indicated that effluent pH and COD influenced the distribution of the primary hydrogen-producing bacteria, including Ethanoligenens, Raoultella, and Pectinatus, as well as other low abundant hydrogen-producing bacteria in the activated sludge. The data indicates that the multiple pretreatments and reactor's operation has successfully enriched the hydrogen-producing genera and changed the community structure of microbial hydrogen production.

Superhydrophilic 3D amorphous/crystalline heterostructure: Nanosheets-assembled CoMoP-FexP/NF as efficient bifunctional electrodes for alkaline water splitting

To push forward the hydrogen energy technology, it is crucial to develop a highly active catalyst for the application of water splitting. Nevertheless, many electrocatalysts suffer from functional limitations, making them unsuitable for both anode and cathode applications. Therefore, the utilization of bifunctional electrocatalysts is necessary to overcome this limitation. In this study, we have reported a bifunctional CoMoP-FexP/NF catalyst with favorable electrocatalytic performance toward hydrogen evolution reaction/oxygen evolution reaction (HER/OER). Balanced amorphous/crystalline heterophase endows CoMoP-FexP/NF with more exposed active sites. In addition, the superhydrophobic nature of CoMoP-FexP/NF helps to improve the contact with electrolyte. Following conditional optimization, CoMoP-FexP/NF requires only an overpotential of 85.6 mV to achieve a current density of 10 mA cm−2 for HER, and 249.6 mV for a current density of 20 mA cm−2 for OER. A water-splitting electrolyzer comprising CoMoP-FexP/NF requires a low cell voltage of 1.56 V to achieve a current density of 10 mA cm−2. This study provides valuable insights into designing bifunctional electrocatalysts and replacing noble metallic materials to enhance hydrogen production from water splitting.

Advancing Catalysts by Stacking Fault Defects for Enhanced Hydrogen Production: A Review.

Green hydrogen, derived from water splitting powered by renewable energy such as solar and wind energy, provides a zero-emission solution crucial for revolutionizing hydrogen production and decarbonizing industries. Catalysts, particularly those utilizing defect engineering involving the strategical introduction of atomic-level imperfections, play a vital role in reducing energy requirements and enabling a more sustainable transition toward a hydrogen-based economy. Stacking fault (SF) defects play an important role in enhancing the electrocatalytic processes by reshaping surface reactivity, increasing active sites, improving reactants/product diffusion, and regulating electronic structure due to their dense generation ability and profound impact on catalyst properties. This review explores SF in metal-based materials, covering synthetic methods for the intentional introduction of SF and their applications in hydrogen production, including oxygen evolution reaction, photo- and electrocatalytic hydrogen evolution reaction, overall water splitting, and various other electrocatalytic processes such as oxygen reduction reaction, nitrate reduction reaction, and carbon dioxide reduction reaction. Finally, this review addresses the challenges associated with SF-based catalysts, emphasizing the importance of a detailed understanding of the properties of SF-based catalysts to optimize their electrocatalytic performance. It provides a comprehensive overview of their various applications in electrocatalytic processes, providing valuable insights for advancing sustainable energy technologies.

Tailoring hydrophilicity and electronic interactions and transfer: Enhancing hydrogen production through size-tuned CuNi alloys

Investigating eco-friendly, effective, and economical cocatalysts for photocatalytic hydrogen evolution remains a significant challenge. In this research, different methods were utilized to synthesize CuNi nanoalloys of varied particle sizes supported on Al-doped SrTiO3 (Al-STO), delving into the effects of CuNi alloy particle size, catalyst material hydrophilicity, and charge dynamics on photocatalytic efficiency. The study meticulously examined how different particle sizes of CuNi alloys impacted the photocatalytic activity of Al-STO, noting that larger CuNi alloy nanoparticles significantly enhance and stabilize photocatalytic hydrogen evolution, achieving a rate of 58.14 µmol/h. A detailed comparative analysis was also conducted, focusing on the nanoalloys' distribution, elemental composition, and optical characteristics, thereby elucidating the critical role of particle size in influencing the physicochemical properties of CuNi nanoalloys. Furthermore, comprehensive Density Functional Theory (DFT) calculations were carried out to confirm the robust interactions between the alloy and support, as well as the electronic synergies within the CuNi alloy components. These interactions are shown to greatly affect charge transfer efficiency and the adsorption energy of the reactants, such as water molecules. This investigation paves the way for adopting non-precious bimetallic cocatalysts in efficient photocatalytic hydrogen production, offering valuable insights for future clean energy research endeavors.

Flocculation-enhanced photobiological hydrogen production by microalgae: Flocculant composition, hydrogenase activity and response mechanism

The practical application of microalgal photobiological hydrogen was limited by its low yield and short production time. In this study, the promotion of inorganic flocculants (polymeric aluminum chloride, PAC) and organic flocculants (cationic polyacrylamide, CPAM) to the aggregate formation and photobiological hydrogen production of prokaryotic microalgae (Synechocystis sp.) and eukaryotic microalgae (Chlamydomonas reinhardtii) were investigated. The effectiveness of PAC-CPAM composite flocculants in promoting aggregation was compared to single PAC or CPAM, with flocculation efficiencies exceeding 92.2 % for both microalgal strains. After aggregate formation, hydrogen production in Synechocystis and C. reinhardtii increased by 65.9 % and 80.2 %, respectively, compared with the control (without flocculation). Their hydrogenase activity rose to 1.14 and 28.2 μmol H2/(mg chlorophyll·h), respectively. Aggregation sustained the photosynthetic activity of both Synechocystis and C. reinhardtii, with the photosynthetic system electron transfer rate (ETR) 1.54–1.72 times higher than that of the control. The formation of aggregates enhanced microalgal respiration, accelerating the reduction of oxygen content, and increasing hydrogenase activity. Notably, the increased respiration in Synechocystis and C. reinhardtii aggregates supplied more electrons, enhancing hydrogen production by consuming intracellular organic matter. Aggregate formation upregulated the expression of Synechocystis and C. reinhardtii hydrogenase genes by average 2.1-fold and 2.5-fold, respectively. Simultaneously, the expression of genes related to photosynthetic system Ⅱ, ferredoxin, pyruvate ferredoxin-oxidoreductase, and oxidative phosphorylation were upregulated, with a significant effect observed in C. reinhardtii aggregates. The results of this study advanced the utilization and industrialization of microalgae-based green hydrogen production, contributing to carbon neutrality.

Novel design of in-situ hydrogen sorption/storage integrated enhanced hydrogen production in supercritical CO2 gasification, air gasification, and steam gasification from biomass

The novel process on in-situ hydrogen sorption/storage during water gas shift (WGS) was proposed and the enhanced hydrogen production in supercritical CO2 gasification (CG), air gasification (AG), and steam gasification (SG) from biomass was integrated. Pure hydrogen was obtained by regeneration from the material (Mg2Ni) used for in-situ H2 absorption during WGS. The effects of temperature, pressure, steam-to-carbon (S/C) ratio, and the quantity of adsorbent for the enhanced hydrogen production with in-situ hydrogen sorption/storage were determined. When Mg2Ni was added as the in-situ H2 adsorbent, the hydrogen conversion in WGS reaction was improved. The increase of temperature reduced the hydrogen yield. SG presented the highest hydrogen yield and AG showed the highest hydrogen conversion. The steam-to-carbon (S/C) had a positive effect on the hydrogen production for all the processes and the methanation reaction was greatly inhibited by AG. The energy efficiencies reached 22.98 %, 26.31 %, and 27.149.51 %, and the exergy efficiencies reached 61.66 %, 64.19 %, and 83.62 %, for CG, AG and SG, respectively. The system energy can be supplied by in-situ hydrogen sorption/storage and the energy requirement order was SG > CG > AG.

Laser-Synthesized Co-Doped CuO Electrocatalyst: Unveiling Boosted Methanol Oxidation Kinetics for Enhanced Hydrogen Production Efficiency by In Situ/Operando Raman and Theoretical Analyses.

The present study details the strategic development of Co-doped CuO nanostructures via sophisticated and expedited pulsed laser ablation in liquids (PLAL) technique. Subsequently, these structures are employed as potent electrocatalysts for the anodic methanol oxidation reaction (MOR), offering an alternative to the sluggish oxygen evolution reaction (OER). Electrochemical assessments indicate that the Co-CuO catalyst exhibits exceptional MOR activity, requiring a reduced potential of 1.42V at 10 mAcm-2 compared to that of pure CuO catalyst (1.57V at 10 mAcm-2). Impressively, the Co-CuO catalyst achieved a nearly 180mV potential reduction in MOR compared to its OER performance (1.60V at 10 mA cm-2). Furthermore, when pairing Co-CuO(+)ǀǀPt/C(-) in methanol electrolysis, the cell voltage required is only 1.51V at 10 mAcm-2, maintaining remarkable stability over 12h. This represents a substantial voltage reduction of ≈160mV relative to conventional water electrolysis (1.67V at 10 mAcm-2). Additionally, both in situ/operando Raman spectroscopy studies and theoretical calculations have confirmed that Co-doping plays a crucial role in enhancing the activity of the Co-CuO catalyst. This research introduces a novel synthetic approach for fabricating high-efficiency electrocatalysts for large-scale hydrogen production while co-synthesizing value-added formic acid.