1 Copper bismuth oxide (CuBi2O4): Synthesis, properties and potential applications 1 Copper bismuth oxide (CuBi2O4) is a p-type semiconductor which is an outstanding representative of the spinel-type compounds. In the present article, various methods used for the synthesis of CuBi2O4 such as hydrothermal, co-precipitation, microwave-assisted, mechanochemical, solid-state etc. with the feature(s) of the product obtained have been summarized. Furthermore, the promising potential applications of CuBi2O4 such as in gas sensing, as a photocatalyst, as a photocathode material, in activating certain oxidants such as peroxymonosulfate and H2O2, and for various other applications have also been reviewed. Such compiled study will be useful to specialists dealing with CuBi2O4 and is also expected to promote the further application of CuBi2O4. 1 12 Saifullahi Shehu Imam Department of Pure and Industrial Chemistry, Bayero University P.M.B 3011 Nigeria ssimam.chm@buk.edu.ng CuBi2O4 Synthesis Hydrothermal Photocatalyst Band-gap Article1.pdf [1] N. Henry, O. Mentre, J. Boivin, F. Abraham, Local Perturbation in Bi2CuO4: Hydrothermal Synthesis, Crystal Structure, and Characterization of the New Bi2 (Cu1-2 x M x) O4 (M= Bi, Pb), Chemistry of materials, 13 (2001) 543-551.##[2] F. Wang, H. Yang, Y. Zhang, Enhanced photocatalytic performance of CuBi2O4 particles decorated with Ag nanowires, Materials Science in Semiconductor Processing, 73 (2018) 58-66.##[3] F.E. Oropeza, N.Y. Dzade, A. Pons-Martí, Z. Yang, K.H. Zhang, N.H. De Leeuw, E.J. Hensen, J.P. Hofmann, Electronic structure and interface energetics of CuBi2O4 photoelectrodes, The Journal of Physical Chemistry C, 124 (2020) 22416-22425.##[4] Z. Li, M. Chen, Q. Zhang, D. Tao, Mechanochemical synthesis of a Z-scheme Bi2WO6/CuBi2O4 heterojunction and its visible-light photocatalytic degradation of ciprofloxacin, Journal of Alloys and Compounds, 845 (2020) 156291.##[5] Y.-H. Choi, D.-H. Kim, S.-H. Hong, CuBi2O4 prepared by the polymerized complex method for gas-sensing applications, ACS applied materials interfaces, 10 (2018) 14901-14913.##[6] S.P. Berglund, F.F. Abdi, P. Bogdanoff, A. Chemseddine, D. Friedrich, R. Van De Krol, Comprehensive evaluation of CuBi2O4 as a photocathode material for photoelectrochemical water splitting, Chemistry of Materials, 28 (2016) 4231-4242.##[7] D. Kang, J.C. Hill, Y. Park, K.-S. Choi, Photoelectrochemical properties and photostabilities of high surface area CuBi2O4 and Ag-doped CuBi2O4 photocathodes, Chemistry of Materials, 28 (2016) 4331-4340.##[8] F. Wang, W. Septina, A. Chemseddine, F.F. Abdi, D. Friedrich, P. Bogdanoff, R. Van De Krol, S.D. Tilley, S.P. Berglund, Gradient self-doped CuBi2O4 with highly improved charge separation efficiency, Journal of the American Chemical Society, 139 (2017) 15094-15103.##[9] F. Guo, W. Shi, H. Wang, M. Han, W. Guan, H. Huang, Y. Liu, Z. Kang, Study on highly enhanced photocatalytic tetracycline degradation of type Ⅱ AgI/CuBi2O4 and Z-scheme AgBr/CuBi2O4 heterojunction photocatalysts, Journal of hazardous materials, 349 (2018) 111-118.##[10] G. Sharma, Z. Zhao, P. Sarker, B.A. Nail, J. Wang, M.N. Huda, F.E. Osterloh, Electronic structure, photovoltage, and photocatalytic hydrogen evolution with p-CuBi 2 O 4 nanocrystals, Journal of Materials Chemistry A, 4 (2016) 2936-2942.##[11] J. Liu, L. Huang, Y. Li, J. Yao, S. Shu, L. Huang, Y. Song, Q. Tian, Constructing an S-scheme CuBi2O4/Bi4O5I2 heterojunction for light emitting diode-driven pollutant degradation and bacterial inactivation, Journal of Colloid and Interface Science, 621 (2022) 295-310.##[12] H. Gao, F. Wang, S. Wang, X. Wang, Z. Yi, H. Yang, Photocatalytic activity tuning in a novel Ag2S/CQDs/CuBi2O4 composite: Synthesis and photocatalytic mechanism, Materials Research Bulletin, 115 (2019) 140-149.##[13] H. Yin, M.-L. Cao, X.-X. Yu, C. Li, Y. Shen, M.-Q. Zhu, Hierarchical CuBi 2 O 4 microspheres as lithium-ion battery anodes with superior high-temperature electrochemical performance, RSC advances, 7 (2017) 13250-13256.##[14] Y.-H. Choi, D.-H. Kim, S.-H. Hong, Gas sensing properties of type CuBi2O4 porous nanoparticulate thin film prepared by solution process based on metal-organic decomposition, Sensors and Actuators B: Chemical, 268 (2018) 129-135.##[15] M. Chen, Q. Yang, L. Li, M. Liu, P. Xiao, M. Zhang, Solid-state synthesis of CuBi2O4/MWCNT composites with enhanced photocatalytic activity under visible light irradiation, Materials Letters, 171 (2016) 255- 258.##[16] Y. Xie, Y. Zhang, G. Yang, C. Liu, J. Wang, Hydrothermal synthesis of CuBi2O4 nanosheets and their photocatalytic behavior under visible light irradiation, Materials letters, 107 (2013) 291-294.##[17] L.S. Ribeiro, I.M. Pinatti, J.A. Torres, A.S. Giroto, F. Lesse, E. Longo, C. Ribeiro, A.E. Nogueira, Rapid microwave-assisted hydrothermal synthesis of CuBi2O4 and its application for the artificial photosynthesis, Materials Letters, 275 (2020) 128165.##[18] X. Zhang, S. Wang, L. Lin, X. Tan, Y. Zeng, Design of a novel CuBi2O4/CdMoO4 heterojunctions with nano-microsphere structure:Synthesis and photocatalytic degradation mechanism, Colloids and Surfaces A: Physicochemical and Engineering Aspects, 614 (2021) 126008.##[19] A. Abdulkarem, J. Li, A. Aref, L. Ren, E. Elssfah, H. Wang, Y. Ge, Y. Yu, CuBi2O4 single crystal nanorods prepared by hydrothermal method: Growth mechanism and optical properties, Materials Research Bulletin, 46 (2011) 1443-1450.##[20] Y. Deng, Y. Chen, B. Chen, J. Ma, Preparation, characterization and photocatalytic activity of CuBi2O4/NaTaO3 coupled photocatalysts, Journal of alloys and compounds, 559 (2013) 116-122.##[21] S. Wu, X. Yu, J. Zhang, Y. Zhang, Y. Zhu, M. Zhu, Construction of BiOCl/CuBi2O4 S-scheme heterojunction with oxygen vacancy for enhanced photocatalytic diclofenac degradation and nitric oxide removal, Chemical Engineering Journal, 411 (2021) 128555.##[22] F. Guo, M. Li, H. Ren, X. Huang, W. Hou, C. Wang, W. Shi, C. Lu, Fabrication of pn CuBi2O4/MoS2 heterojunction with nanosheets-onmicrorods structure for enhanced photocatalytic activity towards tetracycline degradation, Applied Surface Science, 491 (2019) 88-94.##[23] X. Yuan, D. Shen, Q. Zhang, H. Zou, Z. Liu, F. Peng, Z-scheme Bi2WO6/CuBi2O4 heterojunction mediated by interfacial electric field for efficient visible-light photocatalytic degradation of tetracycline, Chemical Engineering Journal, 369 (2019) 292-301.##[24] H. Shi, J. Fan, Y. Zhao, X. Hu, X. Zhang, Z. Tang, Visible light driven CuBi2O4/Bi2MoO6 pn heterojunction with enhanced photocatalytic inactivation of E. coli and mechanism insight, Journal of hazardous materials, 381 (2020) 121006.##[25] J. Luo, X. Zhou, F. Yang, X. Ning, L. Zhan, Z. Wu, X. Zhou, Generating a captivating S-scheme CuBi2O4/CoV2O6 heterojunction with boosted charge spatial separation for efficiently removing tetracycline antibiotic from wastewater, Journal of Cleaner Production, 357 (2022) 131992.##[26] Y. Wang, F. Cai, P. Guo, Y. Lei, Q. Xi, F. Wang, Short-time hydrothermal synthesis of CuBi2O4 nanocolumn arrays for efficient visiblelight photocatalysis, Nanomaterials, 9 (2019) 1257.##[27] W. Shi, M. Li, H. Ren, F. Guo, X. Huang, Y. Shi, Y. Tang, Construction of a 0D/1D composite based on Au nanoparticles/CuBi2O4 microrods for efficient visible-light-driven photocatalytic activity, Beilstein Journal of Nanotechnology, 10 (2019) 1360-1367.##[28] C. Fang, H. Su, M. Hu, Z. Jiang, L. Xu, C. Liu, Construction and performance of a novel CuBi2O4/In2O3 Z-scheme heterojunction photocatalyst, Materials Science in Semiconductor Processing, 160 (2023) 107464.##[29] N. Li, H. Du, M. Tan, L. Yang, B. Xue, S. Zheng, Q. Wang, Construction of Z-scheme CuBi2O4/MIL-88A (Fe) heterojunctions with enhanced LED light driven photocatalytic Cr (VI) reduction and antibacterial performance, Applied Surface Science, 614 (2023) 156249.##[30] C. Lu, L. Wang, D. Yang, Z. Jin, X. Wang, J. Xu, Z. Li, W. Shi, W. Guan, W. Huang, Boosted tetracycline and Cr (VI) simultaneous cleanup over Z-Scheme BiPO4/CuBi2O4 pn heterojunction with 0D/1D trepang-like structure under simulated sunlight irradiation, Journal of Alloys and Compounds, 919 (2022) 165849.##[31] J.-X. Mao, J.-C. Wang, H. Gao, W. Shi, H.-P. Jiang, Y. Hou, R. Li, W. Zhang, L. Liu, S-scheme heterojunction of CuBi2O4 supported Na doped P25 for enhanced photocatalytic H2 evolution, International Journal of Hydrogen Energy, 47 (2022) 8214-8223.##[32] X. Chen, Y. Dai, J. Guo, Hydrothermal synthesis of well-distributed spherical CuBi2O4 with enhanced photocatalytic activity under visible light irradiation, Materials Letters, 161 (2015) 251-254.##[33] H. Ramezanalizadeh, E. Rafiee, Design, fabrication, electro-and photoelectrochemical investigations of novel CoTiO3/CuBi2O4 heterojunction semiconductor: An efficient photocatalyst for the degradation of DR16 dye, Materials Science in Semiconductor Processing, 113 (2020) 105055.##[34] K. Song, C. Zhang, Y. Zhang, G. Yu, M. Zhang, Y. Zhang, L. Qiao, M. Liu, N. Yin, Y. Zhao, Efficient tetracycline degradation under visible light irradiation using CuBi2O4/ZnFe2O4 type II heterojunction photocatalyst based on two spinel oxides, Journal of Photochemistry and Photobiology A: Chemistry, 433 (2022) 114122.##[35] Z. Zhang, H. Hao, H. Yang, L. Zhu, C. Ding, G. Zhang, J. Bi, S. Yan, G. Liu, H. Hou, UV-Vis-NIR-light-driven Ag2O/Ag2S/CuBi2O4 double Z-scheme configuration for enhanced photocatalytic applications, Materials Science in Semiconductor Processing, 126 (2021) 105668.##[36] P. Annamalai, D. Thangavelu, M. Ramadoss, S. Subramani, S.P. Muthu, R. Perumalsamy, S. Ranganathan, V. Hector, Electrochemical sensing of tyrosine and removal of toxic dye using self-assembled threedimensional CuBi2O4/rGO microsphere composite, Colloid and Interface Science Communications, 45 (2021) 100523.##[37] Z. Zhang, X. Hao, S. Hao, J. Li, Preparation of Pd@ CuBi2O4 photocatalysts and their performance for selective oxidation of benzyl alcohol under visible light illumination, Materials Science in Semiconductor Processing, 142 (2022) 106499.##[38] R. Muankaew, C. Banphot, P. Thammaacheep, P. Jannoey, W. Khanitchaidecha, A. Nakaruk, D. Channei, Synthesis of Flower-Like CuBi2O4 Microspheres and Its Photocatalytic Activity, Trends in Sciences, 21 (2024) 7200-7200.##[39] T. Ma, H. Long, Z. Shi, Z. Lang, M. Zhao, S. Zhang, C. Lei, Efficient photocatalytic degradation of TC under visible light with threedimensional flower shaped N doped BiOBr/CuBi2O4, Optical Materials, 143 (2023) 114175.##[40] A.C. Nogueira, L.E. Gomes, J.A. Ferencz, J.E. Rodrigues, R.V. Goncalves, H. Wender, Improved visible light photoactivity of CuBi2O4/CuO heterojunctions for photodegradation of methylene blue and metronidazole, The Journal of Physical Chemistry C, 123 (2019) 25680- 25690.##[41] X. Chen, N. Li, S. Xu, H. Wang, Y. Cai, Study on the visible-light photocatalytic performance and degradation mechanism of diclofenac sodium under the system of hetero-structural CuBi2O4/Ag3PO4 with H2O2, Materials, 11 (2018) 511.##[42] Y. Cao, T. He, M. Li, Z. Cao, Y. Gao, J. Liu, G. Li, A novel strategy to enhance the visible light driven photocatalytic activity of CuBi2O4 through its piezoelectric response, Journal of Physics and Chemistry of Solids, 167 (2022) 110732.##[43] Y. Zhou, H. Deng, Z. Li, Y. Wang, T. Ma, Construction of CuBi2O4/BiOBr/Biochar Z-Scheme Heterojunction for Degradation of Gaseous Benzene Under Visible Light, Catalysis Letters, 153 (2023) 2319- 2330.##[44] T. Arai, M. Yanagida, Y. Konishi, Y. Iwasaki, H. Sugihara, K. Sayama, Efficient complete oxidation of acetaldehyde into CO2 over CuBi2O4/WO3 composite photocatalyst under visible and UV light irradiation, The Journal of Physical Chemistry C, 111 (2007) 7574-7577.##[45] H. Lahmar, M. Benamira, F. Akika, M. Trari, Reduction of chromium (VI) on the hetero-system CuBi2O4/TiO2 under solar light, Journal of Physics and Chemistry of Solids, 110 (2017) 254-259.##[46] N.T. Hahn, V.C. Holmberg, B.A. Korgel, C.B. Mullins, Electrochemical synthesis and characterization of p-CuBi2O4 thin film photocathodes, The Journal of Physical Chemistry C, 116 (2012) 6459-6466.##[47] M. Sun, B. Liu, W. Han, Z. Zhang, M. Xie, CuBi2O4 photocathode with integrated electric field for enhanced H2O2 production, Applied Catalysis B: Environmental, 304 (2022) 120980.##[48] W. Shi, M. Li, X. Huang, H. Ren, F. Guo, Y. Tang, C. Lu, Construction of CuBi2O4/Bi2MoO6 pn heterojunction with nanosheets-onmicrorods structure for improved photocatalytic activity towards broadspectrum antibiotics degradation, Chemical Engineering Journal, 394 (2020) 125009.##[49] W. Shi, F. Guo, S. Yuan, In situ synthesis of Z-scheme Ag3PO4/CuBi2O4 photocatalysts and enhanced photocatalytic performance for the degradation of tetracycline under visible light irradiation, Applied Catalysis B: Environmental, 209 (2017) 720-728.##[50] Z. Li, R. Zheng, S. Dai, T. Zhao, M. Chen, Q. Zhang, In-situ mechanochemical fabrication of pn Bi2MoO6/CuBi2O4 heterojunctions with efficient visible light photocatalytic performance, Journal of Alloys and Compounds, 882 (2021) 160681.##[51] N. Ahmad, J. Anae, M.Z. Khan, S. Sabir, P. Campo, F. Coulon, A novel CuBi2O4/polyaniline composite as an efficient photocatalyst for ammonia degradation, Heliyon, 8 (2022).##[52] V. Dutta, A. Sudhaik, P. Raizada, A. Singh, T. Ahamad, S. Thakur, Q. Van Le, V.-H. Nguyen, P. Singh, Tailoring S-scheme-based carbon nanotubes (CNTs) mediated Ag-CuBi2O4/Bi2S3 nanomaterials for photocatalytic dyes degradation in the aqueous system, Journal of Materials Science Technology, 162 (2023) 11-24.##[53] L. Wang, G. Yang, D. Wang, C. Lu, W. Guan, Y. Li, J. Deng, J. Crittenden, Fabrication of the flower-flake-like CuBi2O4/Bi2WO6 heterostructure as efficient visible-light driven photocatalysts: Performance, kinetics and mechanism insight, Applied Surface Science, 495 (2019) 143521.##[54] A. Muthukrishnaraj, S. Vadivel, I.M. Joni, N. Balasubramanian, Development of reduced graphene oxide/CuBi2O4 hybrid for enhanced photocatalytic behavior under visible light irradiation, Ceramics International, 41 (2015) 6164-6168.##[55] D. Majhi, A.K. Mishra, K. Das, R. Bariki, B. Mishra, Plasmonic Ag nanoparticle decorated Bi2O3/CuBi2O4 photocatalyst for expeditious degradation of 17α-ethinylestradiol and Cr (VI) reduction: Insight into electron transfer mechanism and enhanced photocatalytic activity, Chemical Engineering Journal, 413 (2021) 127506.##[56] A. Sokhansanj, M. Haghighi, M. Shabani, Macroporous flowerlike Bi2O2CO3-CuBi2O4 nanoheterojunction photocatalyst for high concentrated malachite green degradation: influence of nanocomposite composition and sonication approach, Journal of Molecular Liquids, 371 (2023) 121024.##[57] J. Xu, H. Zhang, Z. Fu, Y. Ling, Hydrothermal synthesis of hierarchical CuBi2O4 microspheres with improved gas sensitivity, Ceramics International, 48 (2022) 31519-31527.##[58] J. Yao, Y. Zhang, Z. Dong, Enhanced degradation of contaminants of emerging concern by electrochemically activated peroxymonosulfate: Performance, mechanism, and influencing factors, Chemical Engineering Journal, 415 (2021) 128938.##[59] X. Xu, R. Lin, X. Deng, J. Liu, In situ synthesis of FeOOH-coated trimanganese tetroxide composites catalyst for enhanced degradation of sulfamethoxazole by peroxymonosulfate activation, Separation and Purification Technology, 275 (2021) 119184.##[60] C. Wang, J. Zhao, C. Chen, P. Na, Catalytic activation of PS/PMS over Fe-Co bimetallic oxides for phenol oxidation under alkaline conditions, Applied Surface Science, 562 (2021) 150134.##[61] F. Chen, G.-X. Huang, F.-B. Yao, Q. Yang, Y.-M. Zheng, Q.-B. Zhao, H.-Q. Yu, Catalytic degradation of ciprofloxacin by a visible-lightassisted peroxymonosulfate activation system: Performance and mechanism, Water research, 173 (2020) 115559.##[62] H. Zhang, L.-c. Nengzi, X. Li, Z. Wang, B. Li, L. Liu, X. Cheng, Construction of CuBi2O4/MnO2 composite as Z-scheme photoactivator of peroxymonosulfate for degradation of antibiotics, Chemical Engineering Journal, 386 (2020) 124011.##[63] W.-D. Oh, Z. Dong, T.-T. Lim, Hierarchically-structured Co– CuBi2O4 and Cu–CuBi2O4 for sulfanilamide removal via peroxymonosulfate activation, Catalysis Today, 280 (2017) 2-7.##[64] M. Sabri, A. Habibi-Yangjeh, S. Ghosh, Novel ZnO/CuBi2O4 heterostructures for persulfate-assisted photocatalytic degradation of dye contaminants under visible light, Journal of Photochemistry and Photobiology A: Chemistry, 391 (2020) 112397.##[65] C. Peng, X. Chen, Y. Yang, F. Luo, X. He, Y. Yu, Q. Deng, T. Hu, S. Shan, Y. Zhi, Enhanced catalytic performance of peroxydisulfate activation for Rhodamine B degradation over a novel MIL-68 (Fe)/CuBi2O4 catalyst, Journal of Molecular Liquids, 392 (2023) 123476.##[66] X. Wang, N. Su, X. Wang, D. Cao, C. Xu, X. Wang, Q. Yan, C. Lu, H. Zhao, Fabrication of 0D/1D S-scheme CoO-CuBi2O4 heterojunction for efficient photocatalytic degradation of tetracycline by activating peroxydisulfate and product risk assessment, Journal of Colloid and Interface Science, (2024).##[67] R. Dumitru, S. Negrea, C. Păcurariu, A. Surdu, A. Ianculescu, A. Pop, F. Manea, CuBi2O4 synthesis, characterization, and application in sensitive amperometric/voltammetric detection of amoxicillin in aqueous solutions, Nanomaterials, 11 (2021) 740.##[68] N.S. Gudipati, S. Vanjari, S. Korutla, R.R. Tammineni, S. Challapalli, Electrochemical detection of 4-nitrophenol on nanostructured CuBi2O4 with plausible mechanism supported by DFT calculations, Journal of Environmental Chemical Engineering, 10 (2022) 108758.##[69] Y. Liu, W. Yang, Y. Li, S. Wang, S. Zhan, Fabrication of CuBi2O4/Bi2MoO6 pn heterojunction as synergistic photoelectric catalyst for efficient removal of ciprofloxacin in photo-electro-Fenton-like system, Journal of Water Process Engineering, 52 (2023) 103534.##[70] C. Cheng, X. Wang, Preparation of CuBi2O4 nanosheets as a highcapacity and cycle-stable anode material for Li recharge batteries, Journal of Energy Storage, 93 (2024) 112217.