Freshwater scarcity is a pressing global issue. Solar-driven interfacial evaporation has attracted considerable attention as an efficient and energy-saving approach for freshwater production. In this work, the photothermal conversion mechanism of interfacial evaporation technology is systematically elaborated, and the common material properties of the photothermal conversion and the water transport layer are comprehensively reviewed. At the same time, the latest research progress of condensation recovery devices ar summarized, and the expanded applications in seawater desalination, wastewater treatment, electricity generation, and disinfection/sterilization are discussed. On this basis, the future development direction and challenges of interfacial evaporation technology are proposed. By comprehensively reviewing and analyzing existing research in interfacial evaporation, this study aims to provide theoretical guidance and technical references for high-performance interfacial evaporation system, thereby promote the in-depth development and practical application of interfacial evaporation technology.

Anion exchange membrane (AEM) water electrolysis combines the advantages of alkaline water electrolysis and proton exchange membrane (PEM) water electrolysis, offering a cost-efficient solution with high performance. The catalyst layer (CL), a critical component of AEM cells, remains an area of active research and development, often drawing on insights from PEM fuel cells and electrolysers. Two primary methods for CL fabrication are catalyst-coated membrane (CCM) and catalyst-coated substrate (CCS). Due to the limited heat resistance of AEMs, CCS is more straightforward to fabricate compared to CCM, making it the preferred approach in many studies. However, comparative investigations of CCM and CCS in AEM water electrolysis are scarce. This study aims to address this gap by first exploring CCM fabrication techniques using various commercial membranes. Subsequently, a comprehensive comparison of CCM and CCS in AEM water electrolysis will be conducted under different operating conditions, including electrolyte and pure water supply. Performance metrics such as linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), and durability will be evaluated. Microscopic imaging and theoretical analysis will be employed to elucidate performance differences between CCM and CCS under varied conditions. Furthermore, models of the CL, incorporating reactive site configuration and ion transport within and beyond the AEM, will be developed to provide deeper insights into optimizing AEM performance through appropriate CL fabrication methods. Additionally, the impact of catalyst distribution on specific activity will be investigated, focusing on configurations where catalysts are either sandwiched between the AEM and the porous transport layer or embedded within the porous transport layer. By providing a systematic comparison and theoretical framework, this work aims to guide future advancements in AEM water electrolysis with improved CL fabrication techniques.

The design of earth-abundant, high-performance bifunctional electrocatalysts for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is crucial for sustainable energy technologies, yet balancing active site exposure and structural stability remains challenging. Here, we report a facile two-step wet-impregnation and pyrolysis strategy to synthesize cocoon-like carbon ellipsoids derived from rape pollen, embedding ultrafine cobalt nanoparticles within a nitrogen-doped porous carbon matrix (Co@RPC). This bio-templated approach preserves the pollen morphology, promotes uniform Co nanoparticle dispersion, and provides abundant Co-Nx/ Co-O active sites, while the carbon framework prevents nanoparticle aggregation and ensures structural durability. Benefiting from these synergistic features, the optimized Co@RPC-700 catalyst exhibits outstanding bifunctional activity, achieving an ORR onset potential of 0.96 V and half-wave potential of 0.85 V, surpassing commercial Pt/C, as well as an OER overpotential of only 314 mV at 10 mA cm-2 with a Tafel slope of 68 mV dec-1 , outperforming IrO2. This work demonstrates a scalable, sustainable strategy for biomass-derived Co-N-C electrocatalysts, offering a promising pathway for next-generation water splitting, fuel cells, and metal-air batteries.

Scaling up water electrolysis to high current densities inevitably induces massive gas evolution at electrode interfaces, posing critical challenges to interfacial transport and system stability. While individual bubble dynamics have been extensively studied, the collective behaviors and critical transitions of densely populated bubbles under extreme conditions remain poorly understood. Here we present a synchronized acoustic–visual framework for characterizing hydrogen bubble evolution during alkaline electrolysis, enabling the segmentation of the polarization curve into four distinct regimes: nucleate whisper, resonant growth, cascade detachment, and turbulent film. This regime map constitutes an electrolytic gas evolution curve, an electrochemical analogue of the classical boiling curve. We identify a critical current density at which interfacial gas accumulation triggers a sharp performance inflection. Near this threshold, bubble dynamics exhibit scale-free acoustic energy distributions and clustered detachment behavior, signaling the emergence of self-organized criticality. Our findings establish a mechanistic foundation linking bubble evolution modes, dynamic acoustic fingerprints, and mass transport transitions under extreme electrolysis conditions, offering a new paradigm for monitoring, diagnosing, and optimizing high-rate gas-evolving electrochemical systems.

The increasing demand for hydrogen as a clean energy carrier, alongside rising water scarcity, requires the advancement of innovative and sustainable water sources for hydrogen production. Prior research has investigated forward osmosis for the reliable production of ultrapure water; nonetheless, these approaches encounter considerable obstacles, such as leakage, low water yield, and restricted applicability with specific water sources (e.g., seawater or effluent) and particular electrolyzers like Alkaline (ALK) or Anion Exchange Membrane (AEM) systems 1,2 . Self-damping mechanisms utilizing water evaporation within membrane porosity have mitigated leakage issues; however, they continue to face challenges related to low water production rates and compatibility with only alkaline water electrolyzers (AWE) 3,4 . This study presents a novel compact system utilizing Direct Contact Membrane Distillation (DCMD) to ensure a continuous supply of ultrapure water for a Proton Exchange Membrane (PEM) electrolyzer, derived from difficult water sources including seawater, industrial effluent, and greasy wastewater. The system operates efficiently by utilizing low-grade waste heat or solar energy, thereby improving sustainability and energy efficiency. A mathematical model and optimization techniques are utilized to synchronize water temperature with the necessary mass flux for the membrane and electrolyzer regions. Our experimental and numerical findings indicate that heating seawater to 60°C facilitates hydrogen production at a rate of 717 Nm³/m²/day of membrane area, which is 14 times greater than current leading water membrane systems for hydrogen production from seawater. Increasing the temperature to 80°C results in a hydrogen flux of 1790 Nm³/m²/day, indicating a 24-fold improvement in seawater-based systems and a 4-fold enhancement in effluent water systems allowing for further increasing the electrolyzer area by introducing multiple stakes. This approach also demonstrates versatility and compatibility with multiple electrolyzer types, such as PEM, AEM, and AWE systems. The proposed system is designed for large-scale industrial applications and municipal wastewater treatment, employing commercially available and cost-effective PTFE membranes. The design facilitates accessibility and high performance, rendering it an effective solution for managing complex water streams. This approach provides a sustainable and environmentally friendly alternative, decreasing reliance on freshwater resources and lessening the environmental effects of wastewater disposal. This system integrates advanced water treatment with hydrogen production, addressing the critical water-energy nexus. It provides a viable method for utilizing non-conventional water sources for hydrogen production, thereby advancing sustainable energy and water resource management. References: Cassol, G. S. et al. Ultra-fast green hydrogen production from municipal wastewater by an integrated forward osmosis-alkaline water electrolysis system. Nat Commun 15 , 2617 (2024). Veroneau, S. S. & Nocera, D. G. Continuous electrochemical water splitting from natural water sources via forward osmosis. Proc. Natl. Acad. Sci. U.S.A. 118 , e2024855118 (2021). Xie, H. et al. A membrane-based seawater electrolyser for hydrogen generation. Nature 612 , 673–678 (2022). Liu, T. et al. In-situ direct seawater electrolysis using floating platform in ocean with uncontrollable wave motion. Nat Commun 15 , 5305 (2024).

The ever-expanding variety of porous transport layer (PTLs) has left the community grappling with a fundamental question: How do we truly assess the influence of PTL parameters on overall cell performance? In challenging conventional reliance on isolated bulk parameters, this study introduces an integrated index based on the PTL/catalyst layer (CL) contact line length (CLL). CLL is first calculated in this work and we argue it is central to governing electrochemical activity at the interface. Rather than depending on X-ray computed tomography, we employ an optical surface profiler to directly capture the PTL surface in contact with the catalyst. Using Fuji Prescale, our measurements indicate that the pressure within the membrane electrode assembly reaches approximately 20 MPa, inducing a membrane deformation of around 10 μm as predicted by elastic theory. Image processing via ImageJ and Python enabled the calculation of CLL across various nickel-based PTL configurations—including ordered meshes, random felts, and porous plates. It should be noted that non-noble catalysts for anion exchange membrane water electrolysis (AEMWE) suffer from lower electrical conductivity, which constrain the active region dramatically. Our findings reveal a direct correlation between CLL and key electrochemical performance parameters, such as catalyst layer resistance. Moreover, pore network modeling confirms that CLL outperforms traditional bulk parameters in predicting cell performance. Although provocative, these results compel us to question whether the established bulk metrics are truly adequate, suggesting that rethinking PTL evaluation strategies may be essential for advancing AEMWE technology.

Thermochemical conversion technologies are emerging as one of the most promising approaches to tackle food waste crisis. However, the existing techniques confront significant challenges in terms of syngas selectivity and catalyst stability. This study introduced a cost-effective Joule heating approach utilizing sequential catalysts composed of treated stainless steel (SS) and biochar to optimize syngas production from food waste. This system achieved a syngas yield of 17.64 mmol⋅grice-1, marking a 76.40 % improvement over conventional thermal pyrolysis. The molar ratio of hydrogen (H2) to carbon monoxide (CO) was adjustable from 0.36 to 0.94, offering flexibility for different applications. Over five cycles, the system maintained robust catalytic stability, with only a 9.70 % decrease in syngas yield. Furthermore, the sequential catalysts proved versatile across diverse food wastes, achieving a maximum selectivity of 87.99 vol%. This approach enhanced catalyst activity and stability by promoting the sequential cracking of large oxygenates and reforming small molecules.

Gas bubble evolution plays a pivotal role in water electrolysis. Electrochemical gas evolution reactions operating at high current densities represent a promising future trend for improving efficiency. However, the lack of reliable bubble detection methods in electrochemical gas evolution systems, as well as the limited understanding of bubble behavior at different current levels, hinder a comprehensive understanding of the actual bubble dynamics under various voltage and current conditions. To address this challenge, a novel methodology that utilizes acoustic emission signals is proposed to evaluate bubble behavior in the electrolyzer. The dynamic variations in the amplitude and frequency of the acoustic emissions can be correlated with the different stages of bubble evolution. By combining this acoustic technique with high-speed optical imaging, the relationship between the acoustic signal variations and the characteristics of bubble release under different voltage and current levels can be unvealed. Furthermore, clustering algorithms from machine learning are employed to determine bubble acoustic characteristics under various conditions based on the acoustic variations, which allows for redefining the polarization curve. These findings significantly enhance the understanding of the actual bubble behavior under different voltage and current intensities, going beyond the traditional pool boiling curve-based approach. The results demonstrate that acoustic emission can serve as an effective and non-intrusive tool for monitoring bubble formation in gas evolution reactions, making it particularly valuable for applications in non-transparent electrolyzer cells. This facile operating approach offers a new perspective for studying and optimizing electrochemical gas evolution processes.

Oxygen starvation, which has a possibility to induce cell reversal and carbon corrosion, is an undesirable phenomenon during the operational process of proton exchange membrane fuel cell (PEMFC) engines. In this paper, a series of experiments are performed under multiple loading conditions, which is chosen with the help of polarity curves, with different values of cathode stoichiometry. The current distribution is analyzed with the utilization of contour maps which are drawn based on segmented PEMFC technique, and the experimental phenomenon is analyzed under normal conditions and oxygen starvation conditions. The experimental result suggests a risen critical number of cathode starvation with the rising loading amplitude. Moreover, a concept of critical characteristic line is highlighted in the current contour map of cathode inlet, and a novel diagnosis method is developed. Under the verification conditions, the effectiveness of this novel diagnosis method is verified. This paper aims to point out a potential direction for robust and effective diagnosis of cathode starvation for PEMFC engines.

In the realm of water electrolysis technology, Alkaline Electrolysis Cell (ALK) hydrogen production stands as a pivotal technology, playing a critical role in the pursuit of large-scale green hydrogen production and the achievement of the "dual carbon" objective. Despite its importance, the mass transfer efficiency of commercial porous nickel electrodes currently used in ALK systems is suboptimal. These electrodes, plagued by unstable catalyst loading, typically operate at current densities between 300-500 mA/cm², seldom reaching the desired threshold of 1 A/cm². This limitation hampers the potential of ALK hydrogen production to satisfy industrial-scale hydrogen production demands. In the quest to overcome these limitations, the concept of the Triple Periodic Minimum Surface (TPMS) structure, a cellular architecture mathematically defined and prevalent in natural biological forms such as butterfly wings and beetle shells, is introduced. The TPMS's unique geometry is adept at adapting to mechanical requirements for various applications, including structural and fluidic systems. It allows for versatile manipulation of geometric parameters like aperture size, porosity, and tortuosity, thereby substantially broadening the design possibilities for electrode structures and enhancing the efficiency of gas-liquid and electron transfer. To harness these benefits, we propose the creation of nickel/nickel-iron electrodes using 3D printing technology. These electrodes are characterized by their cross-scale porosity, ordered structure, and adjustable TPMS design. This innovative electrode design significantly augments bubble transport efficiency and mass transfer performance, while also providing additional anchor points for catalysts, thereby enhancing the electrochemical active surface area, intrinsic activity, and stability of the composite catalyst. As a result, these electrodes achieve ampere-level current densities in ALK electrolysis cells, enhancing electrolysis efficiency and reducing energy consumption. Our methodology involves the use of selective laser melting printing technology to fabricate multi-tier nickel/nickel-iron electrodes of varying specifications. These electrodes are then coated with MOOH catalysts using an electrochemical deposition process. Through rigorous testing and comparison of electrochemical performance parameters, we identified the optimal multi-stage nickel/nickel-iron electrode and its composite catalyst. Electrochemical performance tests reveal that, compared to traditional commercial porous nickel electrodes, our 3D printed electrodes decrease overpotential by 14% and improve electrolytic cell efficiency by 10% at a current density of 1 A/cm². Furthermore, these electrodes exhibit minimal degradation after a 500-hour durability test. The demonstrated efficiency and durability of these 3D-printed hierarchical electrodes indicate significant potential for their application in ampere-level alkaline water electrolysis. Figure 1

Global warming intensifies heat stress, posing substantial challenges to cultivated plants and agricultural yield production. The high solar absorptance of soil results in elevated temperatures, pushing plants beyond their ideal growth range. Additionally, this rise in soil temperature accelerates soil moisture evaporation, further aggravating existing water scarcity issues. Common cooling solutions tends to consume significant amounts of water or offer limited cooling capacities. In response, a radiative cooling and moisturizing film composed of biodegradable ethyl-cellulose was developed. With a solar reflectance of 97% and a thermal emissivity of 0.93, this film provides efficient zero-energy cooling for soil surfaces. Field tests have demonstrated that compared to commercial cooling mulch, the radiative cooling film significantly reduces soil temperature and moisture evaporation by 50% and 60%, respectively. Furthermore, it boosts plant growth by 30% by moderating leaf temperatures and augmenting the exposure to reflected sunlight, crucial for photosynthesis on hot days. Global heat-water simulations reveal that the film increases soil moisture preservation by over 80% and alleviates agricultural water scarcity by over 60% in arid regions during hot seasons. This work offers a practical and sustainable solution to mitigate heat stress and promote resilient cultivation practices in the context of global warming.

Liquid desiccant dehumidification technology, driven by renewable energy, presents an energy-efficient solution to dehumidification. However, a large solution amount is always configured to extend the dehumidification process and address the unavailability of renewable energy. This is due to a lack of design guidance regarding the optimal desiccant solution amount. This study aims to address this gap by offering guidelines, with a particular focus on the dehumidification duration. Initially, a benchmark for the solution amount is defined for convenient quantification in further study. Then, a theoretical analysis of the dehumidification degradation process is conducted. Results reveal that dehumidification duration is primarily constrained by the temperature rise of the desiccant solution, rather than the solution amount. Consequently, a natural cooling unit, instead of mechanical cooling, is introduced to remove the temperature rise. Following this guideline, multiplying the benchmark for the solution amount can significantly extend the dehumidification duration from minutes to hours, while increasing it by tens of times can extend further to days. Furthermore, the solution amount can be reduced by over 90% with the design guideline compared to the traditional method. This study paves a way to significantly reduce the solution amount and relevant costs for liquid desiccant dehumidification systems.

Proton exchange membrane (PEM) and anion exchange membrane (AEM) water electrolyzers exhibit superior efficiency and produce higher purity hydrogen compared to traditional alkaline water electrolyzers due to their membrane electrode assembly (MEA) design. However, random structures presented in current MEA designs introduce significant transport resistance for electrons and mass (ion, gas and liquid), consequently degrading the overall performance of electrolyzes. In contrast, ordered MEA structures are characterized by well-defined arrangements of pores, channels or pathways within catalyst layers (CLs), porous transport layers (PTLs), and ion exchange membranes (IEMs). These ordered configurations facilitate efficient highways for the transfer of electrons and mass. Recent diverse ordered MEA designs have demonstrated significant improvements in overall electrochemical efficiency in both PEM and AEM water electrolyzers. In this review, we will examine recent advancements in ordered MEA designs for water electrolyzers focusing on innovations in fabrication methods and interface morphologies, as well as their electrolysis performance. This review may provide comprehensive guidelines for designing ordered MEAs for both PEM and AEM electrolyzers.

Passive cooling technologies are one of the promising solutions to the global energy crisis due to no consumption of fossil fuels during operation. However, the existing radiative and evaporative coolers still have problems achieving daytime subambient cooling while maintaining evaporation over the long term. Here, we propose a self-sustained and insulated radiative/evaporative cooler (SIREC), which consists of a porous polyethylene film (P-PE) at the top, an air layer in the middle, and poly-(vinyl alcohol) hydrogel with lithium bromide (PLH) at the bottom. In particular, the P-PE shows high solar reflectance (R solar = 0.91) and long-wave infrared transmittance (tau LWIR = 0.92), which reflects sunlight while enhancing the direct radiative heat transfer between outer space and PLH (epsilon LWIR = 0.96) for sky radiative cooling. In addition, the desirable vapor permeability (579 s m(-1)) of the P-PE also results in good compatibility with PLH for evaporative cooling (EC). Moreover, the PLH's ability to harvest atmospheric water at night provides self-sustainment for daytime EC. The air layer between P-PE and PLH further enhances the subambient cooling performance of the SIREC. These findings indicate promising prospects for the integration of passive cooling technologies.

The presence of gas bubbles in electrochemical systems, such as water-splitting, significantly increases overpotential and diminishes energy efficiency. High-fidelity simulation holds significant promise to gain mechanistic understanding of bubble dynamics and guide high-performance electrolytic cell design. However, the extreme length scales involved into electrochemical gas evolving systems, from sub-nanometer dictated by the electrical double layer (EDL) to a few centimeters featured by the electrolytic cell, have posed a huge challenge to enable sufficient numerical accuracy and superior computational efficiency. As a result, state-of-the-art numerical approaches either can only simulate a nanoscale computational domain or neglect the electrochemical kinetics within the EDL, impeding an in-depth understanding of how bubbles could intervene with the electrochemical process. In this work, we demonstrate a full-field simulation approach of electrochemical gas evolving reactions that can capture the electrochemical kinetics of the EDL in a centimeter-scale electrolytical cell with the presence of micro-to-millimeter scale bubbles. To resolve all characteristic length scales, the EDL is geometrically decoupled from the electrolytical cell but physically coupled with the bulk electrolyte and gas bubble through a quasi-1D treatment. As a result, the Nernst-Planck-Poisson-Boltzmann model can be rigorously solved in both the EDL and the rest of the electrolytical cell with highly affordable computational cost. Taking hydrogen evolution reaction as an example, we validated our approach by comparing with a variety of existing numerical and experimental results. For the first time, the impact of bubbles on the increase of overpotential observed in experiments can be quantitatively confirmed through numerical simulation. More notably, compared to state-of-the-art high-fidelity simulations, our approach exhibits a remarkable computational efficiency, which reduced the computational time by a factor of 100,000. This work provides a viable solution to simulate electrochemical gas evolving reactions with highly desirable numerical accuracy and unprecedented computational efficiency, which can serve as an effective tool to understand bubble dynamics and guide the design of next-generation electrolytical cells.

Film cooling is one of the essential measures to guarantee the turbine blade's durability. In the film cooling system design process, it is inevitable for researchers to generate the cooling hole mesh in order to perform the CFD simulation of turbine blades. However, generating hundreds of cooling holes' mesh is time-consuming and requires plenty of manual operations. In addition, to implement the optimal film cooling hole distribution, there is a need to develop a parametric design methodology to arrange the position of cooling holes reasonably. The present paper develops an automated film cooling hole mesh generation system, which adopts a matrix dividing strategy to parameterize the film cooling system. The geometrical representation of the cooling-hole distribution is parameterized by m x n matrices. The system first splits the existing block based on the matrix parameters, dividing the blade surface into m x n pieces. Then, it uses a parametric system to design the cooling hole geometry and automatically generates cooling hole blocking lines at the pieces of interest. The cylindrical and fan-shaped hole topology can be automatically generated in the parametric system. Finally, the transfinite interpolation method is used to automatically produce the structured mesh from the blocking lines. This system can also use the above technologies to generate the cooling hole mesh on the tip of rotor blades. The film cooling hole mesh generation system has been integrated into our existing turbine blade design platform (NuFlux), which is designed to implement the fast changing of the 3D blade geometry and automated structured mesh generation. To verify the reliability of the cooling hole meshing system, the computational grids of NASA C3X film-cooled vane and transonic HPT rotor blade with tip cooling injection are produced using the system and examined in the mesh quality check system in NuFlux. The CFD simulation results using the grids are validated against the relevant experimental data. The integration of the cooling hole meshing system makes NuFlux a unique tool which is competent at turbine blade cooling system design optimization.

Generating water from moist air offers a promising approach to sustainability in greenhouses. The generated water can be used for irrigation, and the resulting air can benefit crop cultivation. However, traditional methods for achieving this often rely on high-grade energy sources, such as electricity, resulting in a low energy efficiency. This study introduces a new system driven by low-grade heat at 32 degrees C to improve the energy efficiency. The new system replaces the conventional regeneration component of the liquid desiccant dehumidification system by a forward osmosis unit. The thermo-responsive ionic liquid, Rm-beta-CD/oligo([vbim]TFSI), serves as the draw solution in the forward osmosis unit. It extracts water from a desiccant solution through osmotic pressure differences and separates the water using low-grade heat via liquid-liquid separation. The performance of the new system is assessed and compared with existing systems (vapor compression system and vacuum membrane system) based on the second law of thermodynamics. Results show the exergy efficiency, defined as the ratio of water recovery to exergy consumption, is an order of magnitude higher for the new system compared to existing systems. Following this, a theoretical study is conducted to guide the design of the new system. Findings indicate that the desiccant solution temperature and ionic liquid concentration significantly affect water recovery. Notably, lowering the inlet desiccant solution temperature of the dehumidifier from 25 degrees C to 15 degrees C can increase water recovery sixty-fold, achieving a relative humidity of 65 %, which satisfies most greenhouse requirements. Additionally, the system performs optimally in energy efficiency with CaCl2 solution compared to LiBr solution. This work lays the groundwork for integrating a wider variety of low-grade heat sources into simultaneous dehumidification and water recovery systems designed for greenhouses.