[1] P. K. Pathak, A. K. Yadav, and S. Padmanaban, "Transition toward emission-free energy systems by 2050: Potential role of hydrogen," International Journal of Hydrogen Energy, vol. 48, no. 26, pp. 9921-9927, 2023/03/26/ 2023, doi: https://doi.org/10.1016/j.ijhydene.2022.12.058.

[2] D. I. Okorie and P. K. Wesseh, "Climate agreements and carbon intensity: Towards increased production efficiency and technical progress?," Structural Change and Economic Dynamics, vol. 66, pp. 300-313, 2023/09/01/ 2023, doi: https://doi.org/10.1016/j.strueco.2023.05.012.

[3] G. S. Seck et al., "Hydrogen and the decarbonization of the energy system in europe in 2050: A detailed model-based analysis," Renewable and Sustainable Energy Reviews, vol. 167, p. 112779, 2022/10/01/ 2022, doi: https://doi.org/10.1016/j.rser.2022.112779.

[4] R. Yukesh Kannah et al., "Techno-economic assessment of various hydrogen production methods – A review," Bioresource Technology, vol. 319, p. 124175, 2021/01/01/ 2021, doi: https://doi.org/10.1016/j.biortech.2020.124175.

[5] F. Samimi, T. Marzoughi, and M. R. Rahimpour, "Energy and exergy analysis and optimization of biomass gasification process for hydrogen production (based on air, steam and air/steam gasifying agents)," International Journal of Hydrogen Energy, vol. 45, no. 58, pp. 33185-33197, 2020/11/27/ 2020, doi: https://doi.org/10.1016/j.ijhydene.2020.09.131.

[6] Ö. Tezer, N. Karabağ, A. Öngen, C. Ö. Çolpan, and A. Ayol, "Biomass gasification for sustainable energy production: A review," International Journal of Hydrogen Energy, vol. 47, no. 34, pp. 15419-15433, 2022/04/22/ 2022, doi: https://doi.org/10.1016/j.ijhydene.2022.02.158.

[7] L. M. Quan et al., "Review of the application of gasification and combustion technology and waste-to-energy technologies in sewage sludge treatment," Fuel, vol. 316, p. 123199, 2022/05/15/ 2022, doi: https://doi.org/10.1016/j.fuel.2022.123199.

[8] J. Lee, S. Kim, and G. Kim, "Preparation of gas standards for quality assurance of hydrogen fuel," International Journal of Hydrogen Energy, vol. 47, no. 55, pp. 23471-23481, 2022/06/30/ 2022, doi: https://doi.org/10.1016/j.ijhydene.2022.05.141.

[9] I. Hussain, A. A. Jalil, M. Y. S. Hamid, and N. S. Hassan, "Recent advances in catalytic systems in the prism of physicochemical properties to remediate toxic CO pollutants: A state-of-the-art review," Chemosphere, vol. 277, p. 130285, 2021/08/01/ 2021, doi: https://doi.org/10.1016/j.chemosphere.2021.130285.

[10] X. Yue et al., "Mitigation of indoor air pollution: A review of recent advances in adsorption materials and catalytic oxidation," Journal of Hazardous Materials, vol. 405, p. 124138, 2021/03/05/ 2021, doi: https://doi.org/10.1016/j.jhazmat.2020.124138.

[11] S. Sahebdelfar and M. T. Ravanchi, "Carbon monoxide clean-up of the reformate gas for PEM fuel cell applications: A conceptual review," International Journal of Hydrogen Energy, vol. 48, no. 64, pp. 24709-24729, 2023/07/29/ 2023, doi: https://doi.org/10.1016/j.ijhydene.2022.08.258.

[12] L. Wang et al., "Improved CO-PROX selectivity of CuO/CeO2 catalysts by decorating with lanthanum via surface Cuξ+ redox site," Applied Surface Science, vol. 649, p. 159087, 2024/03/15/ 2024, doi: https://doi.org/10.1016/j.apsusc.2023.159087.

[13] P. Chin, X. Sun, G. W. Roberts, and J. J. Spivey, "Preferential oxidation of carbon monoxide with iron-promoted platinum catalysts supported on metal foams," Applied Catalysis A: General, vol. 302, no. 1, pp. 22-31, 2006/03/21/ 2006, doi: https://doi.org/10.1016/j.apcata.2005.11.030.

[14] K. Wang, Y. Men, W. Liu, and J. Zhang, "Recent progress in catalytical CO purification of H2-rich reformate for proton exchange membrane fuel cells," International Journal of Hydrogen Energy, vol. 48, no. 64, pp. 25100-25118, 2023/07/29/ 2023, doi: https://doi.org/10.1016/j.ijhydene.2022.08.271.

[15] V. D. B. C. Dasireddy, K. Bharuth-Ram, D. Hanzel, and B. Likozar, "Heterogeneous Cu–Fe oxide catalysts for preferential CO oxidation (PROX) in H2-rich process streams," RSC Advances, 10.1039/D0RA06969H vol. 10, no. 59, pp. 35792-35802, 2020, doi: 10.1039/D0RA06969H.

[16] L. Zhou et al., "For more and purer hydrogen-the progress and challenges in water gas shift reaction," Journal of Energy Chemistry, vol. 83, pp. 363-396, 2023/08/01/ 2023, doi: https://doi.org/10.1016/j.jechem.2023.03.055.

[17] E. Baraj, K. Ciahotný, and T. Hlinčík, "The water gas shift reaction: Catalysts and reaction mechanism," Fuel, vol. 288, p. 119817, 2021/03/15/ 2021, doi: https://doi.org/10.1016/j.fuel.2020.119817.

[18] T. Moeini and F. Meshkani, "Facile synthesis of M-CuFe2O4 (M= Al2O3, CeO2, La2O3, ZrO2, Mn2O3) catalysts using a one-pot method and their applications in high-temperature water gas shift reaction," International Journal of Hydrogen Energy, vol. 48, no. 16, pp. 6370-6383, 2023/02/22/ 2023, doi: https://doi.org/10.1016/j.ijhydene.2022.07.045.

[19] Z. Cui et al., "Synergistic effect of Cu+ single atoms and Cu nanoparticles supported on alumina boosting water-gas shift reaction," Applied Catalysis B: Environmental, vol. 313, p. 121468, 2022/09/15/ 2022, doi: https://doi.org/10.1016/j.apcatb.2022.121468.

[20] P. Ebrahimi, A. Kumar, and M. Khraisheh, "A review of recent advances in water-gas shift catalysis for hydrogen production," Emergent Materials, vol. 3, no. 6, pp. 881-917, 2020/12/01 2020, doi: 10.1007/s42247-020-00116-y.

[21] Y.-L. Lee, K.-J. Kim, G.-R. Hong, and H.-S. Roh, "Target-oriented water–gas shift reactions with customized reaction conditions and catalysts," Chemical Engineering Journal, vol. 458, p. 141422, 2023/02/15/ 2023, doi: https://doi.org/10.1016/j.cej.2023.141422.

[22] S.-Y. Ahn, K.-J. Kim, B.-J. Kim, J.-O. Shim, W.-J. Jang, and H.-S. Roh, "Unravelling the active sites and structure-activity relationship on Cu–ZnO–Al2O3 based catalysts for water-gas shift reaction," Applied Catalysis B: Environmental, vol. 325, p. 122320, 2023/05/15/ 2023, doi: https://doi.org/10.1016/j.apcatb.2022.122320.

[23] M. I. Ariëns, L. G. A. van de Water, A. I. Dugulan, E. Brück, and E. J. M. Hensen, "Copper promotion of chromium-doped iron oxide water-gas shift catalysts under industrially relevant conditions," Journal of Catalysis, vol. 405, pp. 391-403, 2022/01/01/ 2022, doi: https://doi.org/10.1016/j.jcat.2021.12.013.

[24] Y. Ye, L. Wang, S. Zhang, Y. Zhu, J. Shan, and F. F. Tao, "The role of copper in catalytic performance of a Fe–Cu–Al–O catalyst for water gas shift reaction," Chemical Communications, vol. 49, no. 39, pp. 4385-4387, 2013.

[25] F. Meshkani and M. Rezaei, "Preparation of nanocrystalline metal (Cr, Al, Mn, Ce, Ni, Co and Cu) modified ferrite catalysts for the high temperature water gas shift reaction," Renewable Energy, vol. 74, pp. 588-598, 2015/02/01/ 2015, doi: https://doi.org/10.1016/j.renene.2014.08.037.

[26] Y. Ye, L. Wang, S. Zhang, Y. Zhu, J. Shan, and F. Tao, "The role of copper in catalytic performance of a Fe–Cu–Al–O catalyst for water gas shift reaction," Chemical Communications, 10.1039/C2CC37416A vol. 49, no. 39, pp. 4385-4387, 2013, doi: 10.1039/C2CC37416A.

[27] O. Yalcin, S. Sourav, and I. E. Wachs, "Design of Cr-Free Promoted Copper–Iron Oxide-Based High-Temperature Water−Gas Shift Catalysts," ACS Catalysis, vol. 13, no. 19, pp. 12681-12691, 2023/10/06 2023, doi: 10.1021/acscatal.3c02474.

[28] H.-C. Wu, T.-C. Chen, J. H. Wu, C.-H. Chen, J.-F. Lee, and C.-S. Chen, "The effect of an Fe promoter on Cu/SiO2 catalysts for improving their catalytic activity and stability in the water-gas shift reaction," Catalysis Science & Technology,
10.1039/C6CY00542J vol. 6, no. 15, pp. 6087-6096, 2016, doi: 10.1039/C6CY00542J.

[29] W. Zhang, A. Vidal-López, and A. Comas-Vives, "Theoretical study of the catalytic performance of Fe and Cu single-atom catalysts supported on Mo2C toward the reverse water–gas shift reaction," Frontiers in chemistry, vol. 11, p. 1144189, 2023.

[30] L. Yang et al., "Highly Active and Selective Multicomponent Fe–Cu/CeO2–Al2O3 Catalysts for CO2 Upgrading via RWGS: Impact of Fe/Cu Ratio," ACS Sustainable Chemistry & Engineering, vol. 9, no. 36, pp. 12155-12166, 2021/09/13 2021, doi: 10.1021/acssuschemeng.1c03551.

[31] Y. Bai and D. Tian, "Mechanism and catalytic activity of the water–gas shift reaction on a single-atom alloy Al1/Cu (111) surface," Nanoscale, 10.1039/D4NR03732D vol. 17, no. 7, pp. 3999-4007, 2025, doi: 10.1039/D4NR03732D.

[32] D.-W. Jeong et al., "A comparison study on high-temperature water–gas shift reaction over Fe/Al/Cu and Fe/Al/Ni catalysts using simulated waste-derived synthesis gas," Journal of Material Cycles and Waste Management, vol. 16, pp. 650-656, 2014.

[33] J. Shin, M. S. Kang, and J. Hwang, "Effects of bio‐syngas CO2 concentration on water‐gas shift and side reactions with Fe‐Cr based catalyst," International Journal of Energy Research, vol. 45, no. 2, pp. 1857-1866, 2021.

[34] J. Shin, M. S. Kang, and J. Hwang, "Effects of bio-syngas CO2 concentration on water-gas shift and side reactions with Fe-Cr based catalyst," International Journal of Energy Research, vol. 45, no. 2, pp. 1857-1866, 2021/02/01 2021, doi: https://doi.org/10.1002/er.5861.

[35] C. Lucas, D. Szewczyk, W. Blasiak, and S. Mochida, "High-temperature air and steam gasification of densified biofuels," Biomass and Bioenergy, vol. 27, no. 6, pp. 563-575, 2004/12/01/ 2004, doi: https://doi.org/10.1016/j.biombioe.2003.08.015.

[36] F. Yan, S.-y. Luo, Z.-q. Hu, B. Xiao, and G. Cheng, "Hydrogen-rich gas production by steam gasification of char from biomass fast pyrolysis in a fixed-bed reactor: Influence of temperature and steam on hydrogen yield and syngas composition," Bioresource Technology, vol. 101, no. 14, pp. 5633-5637, 2010/07/01/ 2010, doi: https://doi.org/10.1016/j.biortech.2010.02.025.
[37] S. A. Roh, "A Study on the Water Gas Shift Reaction of RPF Syngas," Resources Recycling, vol. 30, no. 6, pp. 12-18, 2021.

[38] H. Chu, Q. Li, A. Meng, and Y. Zhang, "Investigation of hydrogen production from model bio-syngas with high CO2 content by water-gas shift reaction," International Journal of Hydrogen Energy, Article vol. 40, no. 11, pp. 4092-4100, 2015, doi: 10.1016/j.ijhydene.2015.01.170.

[39] Ö. Tezer, N. Karabağ, A. Öngen, and A. Ayol, "Syngas production from municipal sewage sludge by gasification Process: Effects of fixed bed reactor types and gasification agents on syngas quality," Sustainable Energy Technologies and Assessments, vol. 56, p. 103042, 2023/03/01/ 2023, doi: https://doi.org/10.1016/j.seta.2023.103042.