High-Throughput Electrospinning System| Multi-bionic Strategies Integration in Cellulose Nanofber-BasedHydrogen-Bonded Ne:twork for Solar-DrivenMetagels with StronWater Evaporation

Team of Associate Professor Zhu Ruofei at Xinjiang University: Multi-bionic cellulose hydrogel with strong hydrogen bonds! Harnessing nature for seawater desalination and solar-driven wastewater purification breakthrough!

Recently, the team of Associate Professor Zhu Ruofei at Xinjiang University published their latest research, "Multi-bionic Strategies Integration in Cellulose Nanofiber-Based Metagels with Strong Hydrogen-Bonded Network for Solar-Driven Water Evaporation", in Advanced Fiber Materials. Although solar-driven interfacial evaporation (SDIE) technology has advanced rapidly in seawater desalination, water evaporation rates remain a persistent bottleneck. Salt ion accumulation and crystallization in specific device areas reduce evaporation efficiency and energy performance, hindering overall evaporation. Thus, salt tolerance and threshold evaporation rates are key challenges for SDIE advancement.This work introduces strong hydrogen bonds to lower water evaporation enthalpy and integrates multi-bionic strategies to address uncontrolled water transport in cellulose hydrogels at the molecular level, enabling efficient, eco-friendly seawater desalination and wastewater purification.

Fig. 1. Design concept of lotus-inspired 3D cellulose hydrogel.

By incorporating hydrophilic inorganic materials onto cellulose nanofibers, an inorganic-organic hydrogen-bonded network was formed. Lotus-like structures were created via cellulose crystal modification and ice-templating to activate surface groups for hydrogen bonding (Fig. 1).The evaporator combines lotus morphology, Janus wettability (superhydrophilic flower and hydrophobic leaf), and plant transpiration, achieving an exceptional evaporation rate of 3.61 kg·m⁻²·h⁻¹ under 1-sun irradiation. The unique lotus shape absorbs additional environmental energy, reaching a maximum evaporation efficiency of 94.94%. The Janus-wettable dual-porous structure provides self-floating capability and unidirectional salt reflux. Notably, the evaporator works efficiently in arid regions with low humidity and is biodegradable and biocompatible.

Fig. 2. Structural analysis of cellulose hydrogel.

SEM images of the cellulose-based hydrogel (Fig. 2) reveal its sponge-like surface structure with micro-sized pores. Additionally, a film-like particle layer on the fiber surface corresponds to carbon black nanoparticles adhered to the evaporator via an aluminum phosphate binder. XRD patterns confirm that the introduction of crosslinkers and binders leads to complete expansion of cellulose molecular chains, increased intermolecular distances, and a transition from cellulose I to cellulose II crystalline forms. FTIR spectra verify the successful incorporation of crosslinkers and binders. The formation of an inorganic-organic hydrogen-bonded network induces a significant blue shift in hydroxyl groups, indicating strong hydrogen bonding interactions. XPS analysis further confirms the infiltration of the aluminum phosphate binder and the successful synthesis of the inorganic-organic hydrogen-bonded network.

Fig. 3. Solar-driven interfacial evaporation performance.

The incorporation of low-cost carbon black nanoparticles significantly enhances the full-spectrum solar absorption of the hydrogel. Under sunlight, the hydrogel’s surface temperature rapidly increases, demonstrating excellent photothermal conversion efficiency (Fig. 3). The lotus-inspired hydrogel exhibits a rapid temperature rise at its center under illumination, gradually stabilizing over time, while the underlying water shows only slight warming. This confirms that photothermal heating is localized at the surface, with additional environmental energy absorption contributing to highly efficient water evaporation.

Fig. 4. Seawater desalination and wastewater purification performance.

Textile dye wastewater is notoriously difficult to treat. In this study, solar-driven hydrogel purification effectively treats simulated reactive brilliant red dye wastewater, significantly reducing absorbance and salt concentration to meet WHO drinking water standards, enabling low-carbon recycling of textile wastewater (Fig. 4). Furthermore, desalination tests using seawater from different regions demonstrate that the hydrogel reduces salinity by three orders of magnitude, far below the limits set by the WHO and U.S. EPA. The hydrophobic bottom layer allows the hydrogel to float, preventing salt accumulation and pore clogging, while purified water evaporates from the surface—greatly extending the material’s lifespan.Molecular dynamics simulations were employed to analyze the role of strong hydrogen bonds in water evaporation within the hydrogel network.

Fig. 5. Outdoor testing and biocompatibility of cellulose hydrogel.

 Additionally, a solar interfacial evaporation device was designed to test real-world applicability. Outdoor experiments conducted at Xinjiang University (Fig. 5) show that under sunlight, the hydrogel’s surface temperature rises quickly, producing condensed clean water. Infrared thermography reveals a distinct temperature gradient between the center and edges, with side and bottom temperatures remaining lower than ambient, highlighting the hydrogel’s environmental adaptability.To assess biodegradability, the hydrogel was buried alongside plastic in soil seeded with plants. Within 30 days, the hydrogel fully degraded, while the purified water from evaporation promoted seed germination, confirming its non-toxicity. Biocompatibility tests using MC3T3-E1 mouse osteoblast precursor cells incubated for 48 hours showed high cell viability, further supporting the material’s eco-friendly and sustainable design, making it a promising candidate for clean water production via green energy.