{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,7]],"date-time":"2026-08-07T15:14:13Z","timestamp":1786115653297,"version":"build-2736575974"},"reference-count":67,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2026,8,2]],"date-time":"2026-08-02T00:00:00Z","timestamp":1785628800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003593","name":"National Council for Scientific and Technological Development","doi-asserted-by":"crossref","award":["307435\/2023-7"],"award-info":[{"award-number":["307435\/2023-7"]}],"id":[{"id":"10.13039\/501100003593","id-type":"DOI","asserted-by":"crossref"}]},{"award":["307435\/2023-7"],"award-info":[{"award-number":["307435\/2023-7"]}],"id":[{"id":"https:\/\/ror.org\/03swz6y49","id-type":"ROR","asserted-by":"publisher"}]},{"name":"Foundation for Science and Technology Support of the State of Pernambuco","award":["APQ-0952-3.14\/24"],"award-info":[{"award-number":["APQ-0952-3.14\/24"]}]},{"name":"Human Resources Program of the Brazilian National Agency of Petroleum, Natural Gas and Biofuels","award":["2025\/03493-5"],"award-info":[{"award-number":["2025\/03493-5"]}]},{"award":["2025\/03493-5"],"award-info":[{"award-number":["2025\/03493-5"]}],"id":[{"id":"https:\/\/ror.org\/00phthq42","id-type":"ROR","asserted-by":"publisher"}]},{"name":"PRH30\/UFPE"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Hydrogen production by alkaline water electrolysis is a promising pathway for sustainable energy systems; however, conventional electrolyzers rely on membranes or diaphragms that increase cost, electrical resistance, and maintenance requirements. This study reports the development and experimental evaluation of a low-cost, membrane-less, flow-by tubular alkaline electrolyzer integrated with a dedicated gas\u2013liquid separation and volumetric gas-measurement system. The electrolyzer was designed, constructed, experimentally validated, and electrochemically characterized using polarization curves. The effects of KOH concentration (0.50\u20132.00 mol L\u22121), electrolyte flow rate (1.00\u20134.00 L min\u22121), and applied voltage (2.20\u20133.20 V) on hydrogen production were investigated through a full factorial 33 experimental design combined with analysis of variance, response surface methodology, and numerical optimization using the desirability function. The applied voltage was identified as the dominant operating variable, followed by KOH concentration and electrolyte flow rate, while significant interactions involving voltage were also observed. The quadratic regression model showed excellent predictive performance (R2 = 0.9614), and within the investigated operating domain, the highest hydrogen production rate was obtained at 2.00 mol L\u22121 KOH, 1.00 L min\u22121 electrolyte flow rate, and 3.20 V, resulting in an experimental hydrogen production rate of 0.4395 mL s\u22121. These findings demonstrate the potential of the proposed membrane-less flow-by electrolyzer as a simplified, low-cost, and experimentally validated platform for investigating and optimizing membrane-less alkaline water electrolysis under the evaluated operating conditions.<\/jats:p>","DOI":"10.3390\/molecules31152688","type":"journal-article","created":{"date-parts":[[2026,8,3]],"date-time":"2026-08-03T06:17:40Z","timestamp":1785737860000},"page":"2688","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Development, Electrochemical Characterization, and Statistical Optimization of a Low-Cost Membraneless Tubular Flow-By Alkaline Electrolyzer for Green Hydrogen Production"],"prefix":"10.3390","volume":"31","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7517-8896","authenticated-orcid":false,"given":"Bruno Augusto Cabral","family":"Roque","sequence":"first","affiliation":[{"name":"Department of Chemical Engineering, Federal University of Pernambuco (UFPE), Av. dos Economistas, s\/n, Recife 50740-590, Brazil"},{"name":"Advanced Institute of Technology and Innovation (IATI), Rua Potira, 31, Recife 50751-310, Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8886-4855","authenticated-orcid":false,"given":"Hugo Morais","family":"Meira","sequence":"additional","affiliation":[{"name":"Advanced Institute of Technology and Innovation (IATI), Rua Potira, 31, Recife 50751-310, Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Valdemir Alexandre","family":"dos Santos","sequence":"additional","affiliation":[{"name":"Advanced Institute of Technology and Innovation (IATI), Rua Potira, 31, Recife 50751-310, Brazil"},{"name":"School of Technology and Communication, Catholic University of Pernambuco (UNICAP), Rua do Pr\u00edncipe, 526, Recife 50050-900, Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mohand","family":"Benachour","sequence":"additional","affiliation":[{"name":"Department of Chemical Engineering, Federal University of Pernambuco (UFPE), Av. dos Economistas, s\/n, Recife 50740-590, Brazil"},{"name":"Advanced Institute of Technology and Innovation (IATI), Rua Potira, 31, Recife 50751-310, Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4746-0560","authenticated-orcid":false,"given":"Leonie Asfora","family":"Sarubbo","sequence":"additional","affiliation":[{"name":"Department of Chemical Engineering, Federal University of Pernambuco (UFPE), Av. dos Economistas, s\/n, Recife 50740-590, Brazil"},{"name":"Advanced Institute of Technology and Innovation (IATI), Rua Potira, 31, Recife 50751-310, Brazil"},{"name":"School of Technology and Communication, Catholic University of Pernambuco (UNICAP), Rua do Pr\u00edncipe, 526, Recife 50050-900, Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,2]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Hakobyan, L., Armenakyan, R., Baghdasaryan, L., Martirosyan, A., and Ratner, S. (2026). Global Climate Change and Regional Vulnerability: Quantifying CO2\u2013Temperature\u2013Precipitation Interactions with a Focus on Armenia. Geographies, 6.","DOI":"10.3390\/geographies6010010"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"116307","DOI":"10.1016\/j.rser.2025.116307","article-title":"Recent Progress in Bio-Hydrogen Production for Sustainable Energy and Chemical Production","volume":"226","author":"Openshaw","year":"2026","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"154100","DOI":"10.1016\/j.ijhydene.2026.154100","article-title":"Hydrogen as an Energy Carrier: Production Pathways, Thermochemical Constraints, and Electrolysis-Based Green Hydrogen Prospects","volume":"220","author":"Subedi","year":"2026","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"109","DOI":"10.1016\/j.gr.2026.04.012","article-title":"Pathways to Net-Zero Emissions: Integrating Concepts, Technologies, Metrics, and Governance for Deep Decarbonization across Global and Brazilian Contexts","volume":"157","author":"Gouveia","year":"2026","journal-title":"Gondwana Res."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.wen.2025.07.004","article-title":"Navigating the Energy Transition in India: Challenges and Opportunities towards Sustainable Energy Goal","volume":"9","author":"Prajapati","year":"2026","journal-title":"Water-Energy Nexus"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"116238","DOI":"10.1016\/j.rser.2025.116238","article-title":"Advancing the Hydrogen Economy: Economic, Technological, and Policy Perspectives for a Sustainable Energy Transition","volume":"226","author":"Delpisheh","year":"2026","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Zheng, X., Zhou, Z., Wang, J., Zhao, Z., and Zhou, J. (2026). Advanced Electrolytic Water Catalysts: A Key Technology Empowering China\u2019s \u201cDual Carbon\u201d Strategy. Catalysts, 16.","DOI":"10.3390\/catal16050475"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"153984","DOI":"10.1016\/j.ijhydene.2026.153984","article-title":"Techno-Economic Perspectives on Hydrogen Production Systems via Using Renewable Energy Resources: A Comprehensive Review","volume":"219","author":"Khalifa","year":"2026","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Bartoli, M., Pirri, C.F., and Bocchini, S. (2025). A Comprehensive Review on Hydrogen Production from Biomass Gasification. Molecules, 31.","DOI":"10.3390\/molecules31010099"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"116194","DOI":"10.1016\/j.rser.2025.116194","article-title":"Green Hydrogen Production: A Review of Technologies, Challenges, and Hybrid System Optimization","volume":"225","author":"Brahim","year":"2026","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"116193","DOI":"10.1016\/j.rser.2025.116193","article-title":"Toward Sustainable Energy: A Comprehensive Review of Hydrogen Production, Storage, and Utilization","volume":"226","author":"Habibi","year":"2026","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Ahmed, K.W., Dobson, A., Habibpour, S., and Fowler, M. (2025). Enhanced NiFe2O4 Catalyst Performance and Stability in Anion Exchange Membrane Water Electrolysis: Influence of Iron Content and Membrane Selection. Molecules, 30.","DOI":"10.3390\/molecules30153228"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"116685","DOI":"10.1016\/j.rser.2025.116685","article-title":"A Comprehensive Review of Green Hydrogen Production via Electrolysis and Thermolysis, and the Prediction of Potential Natural Hydrogen (Aka Gold Hydrogen) Presence Using Machine Learning","volume":"230","author":"Kawrani","year":"2026","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"116119","DOI":"10.1016\/j.rser.2025.116119","article-title":"A Comprehensive Review of Green Hydrogen Production Technologies: Current Status, Challenges, Research Trends and Future Directions","volume":"225","author":"Mansilha","year":"2026","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Petkucheva, E., Borisov, G., Iliev, J., Lefterova, E., and Slavcheva, E. (2025). 3D Multilayered DDM-Modified Nickel Foam Electrode for Advanced Alkaline Water Electrolysis. Molecules, 31.","DOI":"10.3390\/molecules31010069"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"2419","DOI":"10.1039\/D1SE00255D","article-title":"A Membrane-Less Electrolyzer with Porous Walls for High Throughput and Pure Hydrogen Production","volume":"5","author":"Hadikhani","year":"2021","journal-title":"Sustain. Energy Fuels"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"121172","DOI":"10.1016\/j.renene.2024.121172","article-title":"Alkaline Membrane-Free Water Electrolyser for Liquid Hydrogen Production","volume":"233","author":"Yang","year":"2024","journal-title":"Renew. Energy"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"115156","DOI":"10.1016\/j.enconman.2021.115156","article-title":"Membraneless Electrolyzers for the Production of Low-Cost, High-Purity Green Hydrogen: A Techno-Economic Analysis","volume":"254","author":"Manzotti","year":"2022","journal-title":"Energy Convers. Manag."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"101602","DOI":"10.1016\/j.coelec.2024.101602","article-title":"Advancements in Membrane-Less Electrolysis Configurations: Innovations and Challenges","volume":"49","author":"Mateo","year":"2025","journal-title":"Curr. Opin. Electrochem."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"107833","DOI":"10.1016\/j.ultsonch.2026.107833","article-title":"Chladni Figures Reduce Ohmic Losses in Alkaline Electrolysis","volume":"128","author":"Heidary","year":"2026","journal-title":"Ultrason. Sonochem."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Nikoli\u0107, V.M., Dimi\u0107-Mi\u0161i\u0107, K.M., Maslovara, S.L., Popovi\u0107, D.P., Gigov, M.N., Krsti\u0107, S.S., and Mar\u010deta Kaninski, M.P. (2026). Advances in Alkaline Water Electrolysis\u2014The Role of In Situ Ionic Activation in Green Hydrogen Production. Catalysts, 16.","DOI":"10.3390\/catal16010098"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"163444","DOI":"10.1016\/j.cej.2025.163444","article-title":"Membraneless Water Electrolysis Enabled by Flow and Porous Electrode Design for Bubble Separation","volume":"519","author":"Niblett","year":"2025","journal-title":"Chem. Eng. J."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1592","DOI":"10.1039\/C9EE00219G","article-title":"A Versatile and Membrane-Less Electrochemical Reactor for the Electrolysis of Water and Brine","volume":"12","author":"Hashemi","year":"2019","journal-title":"Energy Environ. Sci."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"132779","DOI":"10.1016\/j.fuel.2024.132779","article-title":"Flow-by Membraneless Electrolyzer Designs: A Macroporous Flow Dividing Mesh Enhances Maximum Allowable Electrode Length","volume":"377","author":"Borah","year":"2024","journal-title":"Fuel"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"12580","DOI":"10.1021\/acssuschemeng.2c03038","article-title":"Electrochemical Reduction of CO2 in Tubular Flow Cells under Gas\u2013Liquid Taylor Flow","volume":"10","author":"Bagemihl","year":"2022","journal-title":"ACS Sustain. Chem. Eng."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"437","DOI":"10.1016\/j.ijhydene.2023.08.084","article-title":"Tubular PEM Electrolysis Cells with a 3D-Printed Oxygen Electrode and ALD Catalyst Coating","volume":"49","author":"Laube","year":"2024","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Rynne, O., Dubarry, M., Molson, C., Lepage, D., Pr\u00e9b\u00e9, A., Aym\u00e9-Perrot, D., Rochefort, D., and Doll\u00e9, M. (2019). Designs of Experiments for Beginners\u2014A Quick Start Guide for Application to Electrode Formulation. Batteries, 5.","DOI":"10.3390\/batteries5040072"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"015003","DOI":"10.1088\/2515-7655\/ad92ab","article-title":"Statistical Design of Experiments for Efficient Performance Characterization of Protonic-Ceramic Electrolysis Cells","volume":"7","author":"Rand","year":"2025","journal-title":"J. Phys. Energy"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"521","DOI":"10.1556\/066.2023.00235","article-title":"Methods for Experimental Design, Central Composite Design and the Box\u2013Behnken Design, to Optimise Operational Parameters: A Review","volume":"52","year":"2023","journal-title":"Acta Aliment."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"38983","DOI":"10.1016\/j.ijhydene.2021.09.152","article-title":"Additive Manufacturing of Bipolar Plates for Hydrogen Production in Proton Exchange Membrane Water Electrolysis Cells","volume":"46","author":"Amores","year":"2021","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"202","DOI":"10.1016\/j.apenergy.2018.02.001","article-title":"Fully Printed and Integrated Electrolyzer Cells with Additive Manufacturing for High-Efficiency Water Splitting","volume":"215","author":"Yang","year":"2018","journal-title":"Appl. Energy"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"41865","DOI":"10.1038\/s41598-025-25842-3","article-title":"An Experimentally Validated Model of Electrolyte Effects in Alkaline Water Electrolysis","volume":"15","author":"Pinto","year":"2025","journal-title":"Sci. Rep."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"151751","DOI":"10.1016\/j.ijhydene.2025.151751","article-title":"Theoretical-Experimental Analysis of a Membraneless Electrolyzer for Hydrogen Production","volume":"182","year":"2025","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"989","DOI":"10.1016\/j.gee.2022.06.006","article-title":"Strategic Comparison of Membrane-Assisted and Membrane-Less Water Electrolyzers and Their Potential Application in Direct Seawater Splitting (DSS)","volume":"8","author":"Malek","year":"2023","journal-title":"Green Energy Environ."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"084502","DOI":"10.1149\/1945-7111\/ad6bc5","article-title":"Modeling the Effect of Material Properties on Liquid-Alkaline Water Electrolysis","volume":"171","author":"Lees","year":"2024","journal-title":"J. Electrochem. Soc."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"23089","DOI":"10.1021\/acsomega.5c01163","article-title":"Highly Durable Additively Manufactured Membrane-Free Electrolyzer","volume":"10","author":"Whittingham","year":"2025","journal-title":"ACS Omega"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"100510","DOI":"10.1016\/j.ref.2023.100510","article-title":"Operational and Design Parameters Evaluation to Improve Hydrogen Production Using a Low-Cost Alkaline Water Electrolysis Cell in Direct Combination with a Photovoltaic Cell","volume":"47","author":"Rossi","year":"2023","journal-title":"Renew. Energy Focus"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"378","DOI":"10.1016\/j.ijhydene.2024.04.333","article-title":"Green Hydrogen Production by Photovoltaic-Assisted Alkaline Water Electrolysis: A Review on the Conceptualization and Advancements","volume":"107","author":"Tello","year":"2025","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"85","DOI":"10.14445\/23488360\/IJME-V13I4P107","article-title":"Response Surface Methodology-Based Optimization of Alkaline Water Electrolysis Parameters for Hydrogen Production","volume":"13","author":"Makhanu","year":"2026","journal-title":"Int. J. Mech. Eng."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"643","DOI":"10.1016\/j.ijhydene.2025.04.270","article-title":"Electrochemical and Thermodynamic Analysis of Alkaline Water Electrolysis: Design and Performance Optimization","volume":"128","author":"Umair","year":"2025","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"100606","DOI":"10.1016\/j.mtphys.2022.100606","article-title":"Study the Effect of Lye Flow Rate, Temperature, System Pressure and Different Current Density on Energy Consumption in Catalyst Test and 500W Commercial Alkaline Water Electrolysis","volume":"22","author":"Li","year":"2022","journal-title":"Mater. Today Phys."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"235292","DOI":"10.1016\/j.jpowsour.2024.235292","article-title":"Energy Consumption Model of Flow-through Electrolyzer Considering Mass Transfer Overpotential for Hydrogen Production from Alkaline Water Splitting","volume":"621","author":"Chen","year":"2024","journal-title":"J. Power Sources"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"155486","DOI":"10.1016\/j.cej.2024.155486","article-title":"Statistical Analysis and Comprehensive Optimisation of Zero-Gap Electrolyser: Transitioning Catalysts from Laboratory to Industrial Scale","volume":"498","author":"Attar","year":"2024","journal-title":"Chem. Eng. J."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"110985","DOI":"10.1016\/j.jece.2023.110985","article-title":"Multi-Objective Optimization of Water Electrolysis Based on Coupling Model of Electrochemistry and Multiphase Flow","volume":"11","author":"Duan","year":"2023","journal-title":"J. Environ. Chem. Eng."},{"key":"ref_45","doi-asserted-by":"crossref","unstructured":"Sevim, D., Pilatin, M.Y., Ekinci, S., and Akin, E. (2026). Charge-Consistent Estimation of Hydrogen Production in a Membraneless Alkaline Water Electrolyzer Using Time-Resolved Current Measurements. Appl. Sci., 16.","DOI":"10.3390\/app16126073"},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"535","DOI":"10.1016\/j.ijhydene.2025.02.235","article-title":"Membraneless Electrolyzer Designed Using the Tesla Valve Concept for Hydrogen Production","volume":"113","author":"Zoljalali","year":"2025","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"100765","DOI":"10.1016\/j.cogsc.2023.100765","article-title":"Recent Developments in Membraneless Electrolysis","volume":"40","author":"Manzotti","year":"2023","journal-title":"Curr. Opin. Green Sustain. Chem."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"F3012","DOI":"10.1149\/2.0021611jes","article-title":"Hydrogen Production with a Simple and Scalable Membraneless Electrolyzer","volume":"163","author":"Christian","year":"2016","journal-title":"J. Electrochem. Soc."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"104770","DOI":"10.1016\/j.ijmultiphaseflow.2024.104770","article-title":"Flow Control for Bubble Management in a Membrane-Free Electrolyser","volume":"174","author":"Yang","year":"2024","journal-title":"Int. J. Multiph. Flow"},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"154335","DOI":"10.1016\/j.ijhydene.2026.154335","article-title":"Design, Development, and Performance Analysis of Scalable, Membrane-Less, 3D Printed Electrolyzers for Hydrogen Generation","volume":"222","author":"Khan","year":"2026","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"155392","DOI":"10.1016\/j.ijhydene.2026.155392","article-title":"Multiphysics Modeling and Experimental Validation of a Conventional Alkaline Water Electrolyzer: Analysis of Two-Phase Flow and Electrochemical Performance","volume":"241","author":"Lujan","year":"2026","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_52","doi-asserted-by":"crossref","unstructured":"Majasan, J.O., Cho, J.I.S., Maier, M., Shearing, P.R., and Brett, D.J.L. (2021). Optimisation of Mass Transport Parameters in a Polymer Electrolyte Membrane Electrolyser Using Factorial Design-of-Experiment. Front. Energy Res., 9.","DOI":"10.3389\/fenrg.2021.643587"},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"54","DOI":"10.1186\/s44147-026-00906-x","article-title":"Performance and Analysis of Variance for Alkaline Water Electrolyzer PV-Powered System for Green Hydrogen Production","volume":"73","author":"Ali","year":"2026","journal-title":"J. Eng. Appl. Sci."},{"key":"ref_54","doi-asserted-by":"crossref","unstructured":"Madondo, N.I., Rathilal, S., and Bakare, B.F. (2022). Utilization of Response Surface Methodology in Optimization and Modelling of a Microbial Electrolysis Cell for Wastewater Treatment Using Box\u2013Behnken Design Method. Catalysts, 12.","DOI":"10.3390\/catal12091052"},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"152830","DOI":"10.1016\/j.ijhydene.2025.152830","article-title":"Single-Input Machine Learning for Gas Evolution in Membraneless Alkaline Water Electrolysis: A Comparative Study of Five Regressors","volume":"199","author":"Sevim","year":"2026","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"14625","DOI":"10.1016\/j.ijhydene.2020.03.195","article-title":"Investigation of PEM Electrolyzer Modeling: Electrical Domain, Efficiency, and Specific Energy Consumption","volume":"45","author":"Ramirez","year":"2020","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"124936","DOI":"10.1016\/j.apenergy.2024.124936","article-title":"Comparative Experimental Study of Alkaline and Proton Exchange Membrane Water Electrolysis for Green Hydrogen Production","volume":"379","author":"Wang","year":"2025","journal-title":"Appl. Energy"},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"29909","DOI":"10.1039\/D4TA04762A","article-title":"Activation of Low-Cost Stainless-Steel Electrodes for Efficient and Stable Anion-Exchange Membrane Water Electrolysis","volume":"12","author":"Jiang","year":"2024","journal-title":"J. Mater. Chem. A"},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"820","DOI":"10.1016\/j.ijhydene.2024.12.076","article-title":"Upgrading Hydrogen Production Rate and Energy Efficiency of Alkaline Water Electrolysis under Effect of Magnetic Field","volume":"98","author":"Ayas","year":"2025","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_60","doi-asserted-by":"crossref","unstructured":"Babay, M.-A., Adar, M., Chebak, A., and Mabrouki, M. (2023). Dynamics of Gas Generation in Porous Electrode Alkaline Electrolysis Cells: An Investigation and Optimization Using Machine Learning. Energies, 16.","DOI":"10.3390\/en16145365"},{"key":"ref_61","doi-asserted-by":"crossref","unstructured":"Demirezen, S.\u015e., K\u0131l\u0131\u00e7, A.E., \u00c7elik, S., Ozcan, H., and Amini Horri, B. (2026). Simulation-Based Performance and Cost Optimization of Alkaline Electrolyzers. Energies, 19.","DOI":"10.3390\/en19030835"},{"key":"ref_62","unstructured":"Skoog, D.A., Holler, F.J., and Crouch, S.R. (2018). Principles of Instrumental Analysis, Cengage Learning. [7th ed.]."},{"key":"ref_63","doi-asserted-by":"crossref","unstructured":"G\u00f3recki, K., \u015awitalski, E., and G\u00f3recki, P. (2022). Modeling the Influence of the Electrolyte Concentration on Electrical Characteristics of an Alkaline Electrolyzer. Energies, 15.","DOI":"10.3390\/en15218090"},{"key":"ref_64","doi-asserted-by":"crossref","first-page":"95","DOI":"10.5004\/dwt.2021.26650","article-title":"Multi-Response Factorial Design Optimization of Organic Acid Separation Process Using Electrodialysis with Bipolar Membrane","volume":"214","author":"Andrzejewski","year":"2021","journal-title":"Desalin. Water Treat."},{"key":"ref_65","doi-asserted-by":"crossref","first-page":"159","DOI":"10.1016\/j.gr.2025.01.012","article-title":"Hydrogen-Powered Future: Catalyzing Energy Transition, Industry Decarbonization and Sustainable Economic Development: A Review","volume":"140","author":"Cavalcanti","year":"2025","journal-title":"Gondwana Res."},{"key":"ref_66","doi-asserted-by":"crossref","first-page":"014002","DOI":"10.1088\/2515-7655\/ac3729","article-title":"Faradaic Efficiency in Protonic-Ceramic Electrolysis Cells","volume":"4","author":"Zhu","year":"2022","journal-title":"J. Phys. Energy"},{"key":"ref_67","first-page":"109","article-title":"Enhancing Hydrogen Production Efficiency in Alkaline Water Electrolysis through Biosurfactants, Ultrasound, and Their Synergistic Combination","volume":"124","author":"Bruno","year":"2026","journal-title":"Chem. Eng. Trans."}],"container-title":["Molecules"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1420-3049\/31\/15\/2688\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,6]],"date-time":"2026-08-06T04:17:23Z","timestamp":1785989843000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1420-3049\/31\/15\/2688"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,8,2]]},"references-count":67,"journal-issue":{"issue":"15","published-online":{"date-parts":[[2026,8]]}},"alternative-id":["molecules31152688"],"URL":"https:\/\/doi.org\/10.3390\/molecules31152688","relation":{},"ISSN":["1420-3049"],"issn-type":[{"value":"1420-3049","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,8,2]]}}}