Erdem, Nurseli GörenerCa̧ǧlar, Başarİnan, EceTuna, OzlemFirtina Ertis, IremBilgin Simsek, Esra01. Izmir Institute of Technology2025-09-252025-09-25202697801237502591879-06820960-1481https://doi.org/10.1016/j.renene.2025.124235https://hdl.handle.net/11147/18465Driven by the urgent need for sustainable energy conversion and environmental remediation technologies, the development of multifunctional materials has gained growing interest. Herein, a bifunctional heterostructure was fabricated by depositing copper tungstate (CuWO<inf>4</inf>) spherical particles over hollow tubular graphitic carbon nitride (HTCN) using an ultrasonic-assisted thermal impregnation method. The photocatalytic activities were evaluated through tetracycline degradation and hydrogen evolution tests, while electrochemical measurements were conducted to assess the supercapacitor performance. CuWO<inf>4</inf>@HTCN composite achieved up to 83% degradation efficiency, a hydrogen evolution rate of 2538 μmol g1 h−1, and a specific capacitance of 212 F g1, demonstrating its strong potential as a multifunctional material for solar-driven environmental and energy storage applications. The enhanced photocatalytic performance was attributed to extended visible light absorption ability, efficient charge separation, and suppressed electron–hole recombination resulting from the formation of a Z-scheme heterojunction. Furthermore, the superior capacitance behavior was ascribed to enhanced electrical conductivity and ion transport, enabled by the porous, nitrogen-rich HTCN structure. The increased HTCN content in the composite improved pore accessibility and active site availability while an excessive amount of CuWO<inf>4</inf> reduced electrochemical performance. These results highlight the multifunctional applicability of CuWO<inf>4</inf>@HTCN composite in photocatalytic hydrogen production and supercapacitor systems, emphasizing their relevance for renewable energy technologies. © 2025 Elsevier B.V., All rights reserved.eninfo:eu-repo/semantics/closedAccessCuWO₄Hollow Tubular g-C3N4HydrogenPhotocatalysisSupercapacitorCapacitanceCopper CompoundsDegradationEnergy ConversionEnergy EfficiencyEnvironmental TechnologyHeterojunctionsHydrogen ProductionHydrogen StoragePhotocatalytic ActivityRenewable EnergySustainable DevelopmentTungsten CompoundsBi-FunctionalEnvironmental RemediationGraphitic Carbon NitridesHollow Tubular g-C3N4Multi-Functional MaterialsPhotocatalytic DegradationRemediation TechnologiesSupercapacitor ApplicationSustainable EnergyTubularsSupercapacitorAlternative EnergyCatalysisCompositeElectrical ConductivityElectrochemical MethodEnergy StorageGas ProductionHydrogenPhotodegradationArticle2-s2.0-10501328328110.1016/j.renene.2025.124235