• Energy Research

In this work, solar-heating-induced temperature-based photocatalytic hydrogen evolution reaction (PC-HER) of different photocatalysts (TiO2 P25, g-C3N4, and their loaded Pt) was comprehensively stu...

Thermal and solar energies are two pivotal components in photothermal catalysis, however, their synergistic energy efficiency for a maximum yield is more important but less investigated. Herein, systematic studies unveil the promotion effects of external heat on the excitation and utilization of energetic hot carriers (EHC) on Pt/TiO2 in photothermal catalysis. Onset reaction temperature of a reaction is found to be the key in control of the energy synergy. When the minimum onset reaction temperature of uphill processes is exceeded, a smaller number of active sites on the catalyst are available to EHC, resulting in a suppressed thermal effect. Rational regulation of EHC and thermal energy in photothermal catalysis leads to optimum quantum efficiencies of both dry reforming of methane and reverse water-gas shift reactions at a medium level of temperature. This work provides new insights to balance thermal and solar-driven catalysis to better conduct photothermal catalysis for fossil fuels upgrading.

Metal atoms atomically dispersed on an inorganic metal-based support compose a unique category of single atom catalysts (SACs) and have important applications in catalytic photoreduction reactions, including H2 evolution reaction, CO2 reduction reaction, and N2 reduction reaction. In this minreview, we summarized the typical metal-support interaction (M-SI) patterns for successful anchoring of single-atom metals on metallic compound supports. Subsequently, the contribution of the dispersed single metal atoms and M-SI to photocatalytic reactions with improved activity, selectivity, and stability are highlighted, such as by accelerating charge transfer, regulating band structure of the support, acting as the reductive sites, and/or increasing catalytic selectivity. Finally, some challenges and perspectives of future development are proposed. We anticipate that this minireview will be a beneficial supplement for a comprehensive perception of metal-based material supported SACs and their application in heterogeneous photo-reductive catalysis.

In this work, the cellulose-enriched mesocarp of tangerine peels (TP) and the lignin-enriched epicarp of the peels (e-TPs) were used as examples to unveil the link between the basic components (cellulose, hemicellulose and lignin) in lignocellulosic biomass and catalytic activity of biochar towards peroxymonosulfate (PMS) activation. The TP biochar exhibits sheet-like morphology and high porosity, while the e-TPs biochar shows a bulk morphology. Accordingly, the former outperformed the latter in terms of catalytic degradation of phenol with PMS, attributing to the higher content of cellulose than lignin in the TP precursor, which was further supported by comparing the catalytic activity of biochar prepared from binary mixtures containing different proportions of cellulose and lignin. Nonradical oxidation pathway based on singlet oxygen (1O2) and electron-transfer mechanism was involved in the TP biochar/PMS system and the key role of CO group in biochar for 1O2 generation was computationally demonstrated. Additionally, the unique porous structure and surface chemistry of TP biochar endows it an excellent adsorbent for various organic pollutants. Herein, this work provides an insight into the effect of lignocellulosic biomass source on the catalytic property of biochar, which would be beneficial to screen lignocellulosic biowastes to prepare high-performance biochar for water remediation.

Heteroatom-doping of carbocatalysts has been a powerful strategy to remarkably enhance the catalytic performance. Herein, the underlying nature of N promotional effects on peroxymonosulfate (PMS) activation for phenol removal is understood by combining kinetics analysis with multiple techniques. A strategy using mixed acid oxidation of carbon nanotube (CNT) followed by NH3 treatment is employed to yield a series of catalysts with different N-doping contents but similar fraction of sp2-hybridized carbon and defective degree, endowing with a chance to discriminate the dominant N-containing active sites. The multi-sites kinetics analysis suggests the graphitic N-containing sites as the dominant active sites. The mechanism of the surface-bound reactive species is also discriminated as the dominant reaction mechanism. The insights reported here could provide the methodology to fundamentally understand the heteroatom-doping effects of carbocatalysis.

Urbanization and industrialization have exerted significant adverse effects on water quality, resulting in a growing need for reliable and eco-friendly treatment technologies. Persulfate (PS)-based advanced oxidation processes (AOPs) are emerging as viable technologies to treat challenging industrial wastewaters or remediate groundwater impacted by hazardous wastes. While the generated reactive species can degrade a variety of priority organic contaminants through radical and nonradical pathways, there is a lack of systematic and in-depth comparison of these pathways for practical implementation in different treatment scenarios. Our comparative analysis of reaction rate constants for radical vs. nonradical species indicates that radical-based AOPs may achieve high removal efficiency of organic contaminants with relatively short contact time. Nonradical AOPs feature advantages with minimal water matrix interference for complex wastewater treatments. Nonradical species (e.g., singlet oxygen, high-valent metals, and surface activated PS) preferentially react with contaminants bearing electron-donating groups, allowing enhancement of degradation efficiency of known target contaminants. For byproduct formation, analytical limitations and computational chemistry applications are also considered. Finally, we propose a holistically estimated electrical energy per order of reaction (EE/O) parameter and show significantly higher energy requirements for the nonradical pathways. Overall, these critical comparisons help prioritize basic research on PS-based AOPs and inform the merits and limitations of system-specific applications.

AbstractSolar desalination is a promising solution for alleviating water scarcity due to its low‐cost, environmentally friendly, and off‐grid capabilities. However, simultaneous salt rejection and heat localization remain challenging, as the rapid salt convection often results in considerable heat loss. Herein, this challenge is overcome via a facile design: i) isolating high‐temperature and high‐salt zones by rationally designing morning glory‐shaped wick structures and ii) bridging high‐salt zones and bulk water with low‐tortuosity macrochannels across low‐temperature surfaces. The salinity gradient in the macrochannels passively triggers convective flow, facilitating the rapid transfer of salt ions from the high‐salt zone to the bulk water. Meanwhile, the macrochannels are spatially isolated from the high‐temperature zone, preventing heat loss during salt convection and thereby achieving a high evaporation rate (≈3 kg m−2 h−1) and superior salt rejection even in highly concentrated real seawater. This work provides new insights into salt rejection strategies and advances practical applications for sustainable seawater desalination.