Industrial dye wastewater poses serious environmental and health risks, demanding sustainable remediation strategies. Here, hierarchically porous hollow TiO₂ nanofibers (HNFTis) were fabricated and combined with blue, green, and orange graphene quantum dots (b-GQDs, g-GQDs, o-GQDs) to form heterojunction photocatalysts. Progressive fluorescence redshift of GQDs, induced by surface functionalization and S/B doping, narrows the bandgap and enhances visible-light absorption. Among the composites, 0.5 wt% o-GQDs/HNFTi exhibited the highest photocurrent and lowest charge-transfer resistance and degraded 99.5% of Methylene blue under visible light within 2 h, outperforming pristine HNFTi (77.7%). The synergistic effect of TiO₂ structural engineering and GQD fluorescence tuning demonstrates an effective strategy for designing high-performance photocatalysts for sustainable wastewater treatment.

Industrial dye wastewater poses severe environmental and health risks, creating an urgent demand for efficient and sustainable remediation technologies. Herein, hierarchically porous hollow TiO2 nanofibers (HNFTi) were constructed through electrospinning and coupled with blue-, green-, and orange-emissive graphene quantum dots (b-, g-, and o-GQDs) to fabricate visible-light-responsive heterojunction photocatalysts. By tailoring the surface functional groups and heteroatom doping of GQDs, a progressive fluorescence redshift was achieved, which effectively narrowed the bandgap and extended visible-light absorption. Benefiting from the synergistic effects of the hierarchically porous hollow TiO2 architecture and the fluorescence-tuned GQDs, the resulting composites exhibited enhanced light harvesting, accelerated charge separation, and improved interfacial charge transfer. Among them, the 0.5 wt% o-GQDs/HNFTi composite showed the best photocatalytic performance, delivering a methylene blue degradation efficiency of 99.5% within 2 h under visible-light irradiation, markedly higher than that of pristine HNFTi (77.7%). Photoelectrochemical and Kelvin probe force microscopy analyses further confirmed the promoted carrier dynamics and effective interfacial separation of photogenerated electron-hole pairs. This work provides a feasible strategy for integrating structural engineering and fluorescence modulation to develop high-performance TiO2-based photocatalysts for wastewater treatment.

While integrating greenhouse gas and air pollutant (AP) mitigation is essential for urban sustainability and public health, municipal-level prioritisation of co-control targets remains hindered by fragmented microdata and decoupled emission inventories. Using Jiaxing—a typical industrialised city in the Yangtze River Delta—as a case study, this work develops a two-dimensional H/G screening framework based on a harmonised 2024 integrated emission inventory and enterprise-level environmental statistics. By converting 54 non-zero source categories into an aggregated matrix, the framework evaluates AP contributions (H-score, averaging PM_2.5, NO_x, SO₂, VOCs, and NH₃) against 100-year global warming potential (GWP₁₀₀)-weighted CO₂-equivalent emissions (G-score). The 70th-percentile screening separates coupled co-control candidates (e.g., combined heat and power, thermal power generation, and motor vehicles) from decoupled, pollutant-specific priorities (e.g., industrial solvent use for VOCs, and paved roads for particulate matter (PM)). Spatial mismatch analysis also contrasted VOC-dominant and CO₂-dominant reporting units, cautioning against a single citywide priority list. Application of an observed 75th-percentile abatement benchmark to reporting industrial enterprises identified a benchmark-implied VOC reduction of 7941 tonnes in 2024. This inventory-based screening framework provides a practical, reproducible methodology to separate integrated-review sources from single-dimension priorities and to identify priority sources for subsequent exposure and health co-benefit assessment.