Large-Scale Nanofiber Manufacturing| Electrospinning-based carbon black/BiOBrhierarchical porous fibrous membranes forvisible-light driven solar vapor generationand antibiotics degradation

Professor Dong Shuying from Henan Normal University: Electrospun Bismuth Oxybromide/Carbon Black Hierarchical Porous Fibrous Membrane for Visible-Light Driven Solar Vapor Generation and Antibiotics Degradation

Interfacial solar steam generation (ISSG) is a promising strategy for freshwater production. However, when treating wastewater containing organic pollutants, these organics become concentrated in photothermal materials and mother liquor during evaporation, not only shortening evaporator lifespan but also potentially creating new environmental issues if improperly handled. Combining ISSG with photocatalytic technology can improve light-to-vapor conversion efficiency through photothermal effects, while localized heat accelerates charge transfer in catalytic reactions, enhancing pollutant removal efficiency. Yet preparing efficient, stable, and durable bifunctional solar evaporators remains challenging.

Recently, Professor Dong Shuying's team at Henan Normal University designed a high-performance, highly porous, low-cost bifunctional layered bismuth oxybromide (BiOBr)/carbon black (CB) composite nanofibrous membrane (NMF) through electrospinning and post layer-by-layer assembly. Benefiting from this design, the composite membrane achieved a water evaporation rate of 1.38 kg m⁻² h⁻¹ under one sun illumination, with 96.1% tetracycline (TC) removal and excellent cycling stability. Moreover, the membrane maintained high degradation efficiency in actual water bodies (tap water and Wei River water) across wide pH ranges, demonstrating strong anti-interference capability and offering a new approach for solar interfacial evaporation and wastewater resource recovery. The study was published in Desalination as "Electrospinning-based carbon black/BiOBr hierarchical porous fibrous membranes for visible-light driven solar vapor generation and antibiotics degradation."

Figure 1: Preparation and microstructure characterization of BOB/CB NMF composite membrane.

Figure 1a illustrates the composite membrane fabrication process. Using polyacrylonitrile (PAN) and water-soluble polyvinylpyrrolidone (PVP) as electrospinning solutions, the BOB/CB NMF composite membrane was obtained through electrospinning, simple drop-coating, and hydrothermal in-situ growth. SEM showed CB nanoparticles randomly stacked on the membrane surface, forming slits and narrow pores that enhance light capture and specific surface area while providing abundant nucleation sites for BiOBr. The bottom nanofibrous membrane exhibited uniform layered distribution, with PVP removed during hydrothermal treatment and washing, leaving irregular pores that increase roughness and hydrophilicity.

Figure 2: Photothermal performance characterization.

As shown in Figure 2, in the BOB/CB NMF membrane, photochromic BiOBr generated acidic gases during hydrothermal growth, causing thermal expansion between pores and forming wrinkles that enhance surface roughness, light absorption, and photothermal conversion. 

Figure 3: Evaporation and degradation performance tests.

Figure 4: Outdoor evaporation and long-term stability tests.

The prepared BOB/CB NMF composite membrane demonstrated excellent evaporation-degradation performance and long-term stability in complex real water environments across broad pH ranges, showing significant value for wastewater purification and clean water recovery.