Chemical Scissors Tailored Nano-Tellurium with High-Entropy Morphology for Efficient Foam-Hydrogel-Based Solar Photothermal Evaporators

A tree-like mimetic gel based on nanocellulose chitosan for the efficient solar evaporation and seawater desalination under high salinity conditions

Freshwater scarcity is an urgent global problem, and solar evaporation technology offers a promising solution by utilizing solar energy for water evaporation and condensation. In this study, we present an environmentally friendly biomimetic solar evaporator based on the Donnan effect by combining degradable nanocellulose and the biomass-based material chitosan, where the photothermal layer is made of carboxylated multi-walled carbon nanotubes and carboxymethylcellulose, which exhibits broad-band spectral absorption, excellent light-to-heat conversion, and enhances the Donnan effect and inhibits Cl- damage to the evaporator. Directional freezing technique was utilized to obtain vertically aligned water channels and unique surface structure to enhance the evaporation rate in order to solve the problem of low evaporation rate of concentrated brine. Experiments show that the biomimetic solar evaporator achieves an ultra-high evaporation rate of 3.382 kg m-2 h-1 in simulated seawater under 1 kW m-2 solar radiation and is capable of long-term stable operation in saline environments. This work promotes the development of salt-resistant solar evaporators by virtue of its green, efficient, durable, and sustainable strength, and provides valuable insights for solving the problem of water scarcity in saline and arid regions.

Photothermal Material-Based Solar-Driven Cogeneration of Water and Electricity: An Efficient and Promising Technology

With the increasing demand for fresh-water and electricity in modern society, various technologies are being explored to obtain fresh-water and electricity. Due to advances in materials science, solar-driven interfacial evaporation (SDIE) systems have attracted widespread attention because they require only solar energy, and possess a high evaporation rate and little pollution. The researchers combined energy harvesting measures into the system to output electricity, further improving energy utilization. However, more in-depth research and review remain on using SDIE systems for efficient water-electricity cogeneration. Therefore, the mechanisms of different photothermal materials that utilize solar energy to produce thermal energy are first summarized in this paper. Subsequently, the mechanism and application of thermal, mechanical, chemical, and evaporation energy to produce electrical power in SDIE water-electricity cogeneration systems are discussed. Concurrently, vital mathematical equations and widely used mathematical simulation methods for performance evaluation and practical applications are presented. The design and operation of water-electricity cogeneration systems based on photothermal materials are analyzed and summarized. Based on a review and in-depth understanding of these aspects, the future development direction of cogeneration is proposed to address the problems faced in basic research and practical applications.

Synthesis Strategies for High Entropy Nanoparticles

Nanoparticles (NPs) of high entropy materials (HEMs) have attracted significant attention due to their versatility and wide range of applications. HEM NPs can be synthesized by fragmenting bulk HEMs or disintegrating and recrystallizing them. Alternatively, directly producing HEMs in NP form from atomic/ionic/molecular precursors presents a significant challenge. A widely adopted strategy involves thermodynamically driving HEM NP formation by leveraging the entropic contribution but incorporating strategies to limit NP growth at the elevated temperatures used for maximizing entropy. A second approach is to kinetically drive HEM NP formation by promoting rapid reactions of homogeneous reactant mixtures or using highly diluted precursor dissolutions. Additionally, experimental evidence suggests that enthalpy plays a significant role in driving HEM NP formation processes at moderate temperatures, with the high energy cost of generating additional surfaces and interfaces at the nanoscale stabilizing the HEM phase. This review critically assesses the various synthesis strategies developed for HEM NP preparation, highlighting key illustrative examples and offering insights into the underlying formation mechanisms. Such insights are critical for fine-tuning experimental conditions to achieve specific outcomes, ultimately enabling the effective synthesis of optimized generations of these advanced materials for both current and emerging applications across various scientific and technological fields.

Tree-Inspired Structurally Graded Aerogel with Synergistic Water, Salt, and Thermal Transport for High-Salinity Solar-Powered Evaporation

Solar-powered interfacial evaporation is an energy-efficient solution for water scarcity. It requires solar absorbers to facilitate upward water transport and limit the heat to the surface for efficient evaporation. Furthermore, downward salt ion transport is also desired to prevent salt accumulation. However, achieving simultaneously fast water uptake, downward salt transport, and heat localization is challenging due to highly coupled water, mass, and thermal transport. Here, we develop a structurally graded aerogel inspired by tree transport systems to collectively optimize water, salt, and thermal transport. The arched aerogel features root-like, fan-shaped microchannels for rapid water uptake and downward salt diffusion, and horizontally aligned pores near the surface for heat localization through maximizing solar absorption and minimizing conductive heat loss. These structural characteristics gave rise to consistent evaporation rates of 2.09 kg m-2 h-1 under one-sun illumination in a 3.5 wt% NaCl solution for 7 days without degradation. Even in a high-salinity solution of 20 wt% NaCl, the evaporation rates maintained stable at 1.94 kg m-2 h-1 for 8 h without salt crystal formation. This work offers a novel microstructural design to address the complex interplay of water, salt, and thermal transport.