Hong Chen

To advance carbon neutrality goals, developing green, metal-free catalytic systems for upgrading biomass-derived platform molecules is urgently demanded. The selective aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) constitutes a core transformation route to produce high-value furan fine chemicals, yet highly active, selective and durable nonmetallic catalysts remain challenging to construct. Herein, we report a facile one-pot pyrolysis strategy to fabricate N, P co-doped hierarchical porous carbon catalysts (denoted CNP-X-T), using biowaste chitosan as dual carbon/nitrogen precursor and phytic acid as phosphorus dopant source. Under mild aerobic conditions (110 °C, 1.0 MPa O₂, 10 h), the optimal CNP-7.5-900 catalyst achieves 99.9% HMF conversion and DFF selectivity of 86.0%. The phosphorus doping simultaneously creates abundant hierarchical micro-mesopores and generates two distinct phosphorus active configurations: electron-donating C₂(N)PO (P₁) and weak Lewis acidic C₂(N)–PO₃ (P₂). Combined density functional theory (DFT) calculations unambiguously unravel a unique synergistic electron-donation–Lewis-acidity catalytic pathway: the P₁ site acts as an electron donor to drastically lower the dissociation barriers of α-C–H and C–OH bonds in HMF, while adjacent P₂ acidic sites polarize hydroxyl groups and suppress undesired side reactions, collaboratively facilitating substrate activation, dehydration and target product desorption. Moreover, CNP-7.5-900 exhibits robust structural and catalytic stability over five consecutive recycling cycles, with negligible decay in activity and selectivity. This work establishes a low-cost, sustainable metal-free heteroatom-carbon catalytic platform for biomass valorization, and delivers a fundamental theoretical guideline for the rational modulation of surface acid-electronic properties to design advanced carbonaceous biomass conversion catalysts.

To achieve carbon neutrality, it is imperative to develop sustainable catalytic systems capable of efficiently upgrading biomass-derived platform chemicals. The selective oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) represents a pivotal transformation in metal-free thermal catalysis. In this study, 99.9% HMF conversion and 86.0% DFF selectivity were achieved under mild conditions (120 ℃, 1.0 MPa O2, 10 h) over the CNP-7.5-900 sample, the catalyst preserved more than 90% conversion and over 80% selectivity across five consecutive cycles, indicative of its exceptional stability and reusability. N, P co-doped porous carbon catalysts (CNP-X-T) were synthesized via a one-pot pyrolysis method using chitosan and phytic acid as the carbon/nitrogen and phosphorus sources, respectively. N, P co-doping created more surface defects, acidic sites, and catalytically active centers with electron-donating P1 sites (C2(N)PO) and acidic P2 sites (C2(N)–PO3). Density functional theory (DFT) calculations revealed a synergistic interplay between electron-donating P1 sites and acidic P2 sites improved the sample property, which strongly correlates with surface acidity. This work establishes a green, metal-free strategy for efficient HMF valorization and provides theoretical and practical guidance for the rational design of heteroatom-engineered carbon catalysts in biomass conversion.

Herein, an Ni ₉ Fe ₁ /NiAlO _z catalyst is reported to be an efficient catalyst for conversion of enzymatic hydrolysis lignin (EHL) and 2-phenethyl phenyl ether (PPE), a lignin dimer model compound.

Biomass is a renewable energy source abundantly available in nature. Their degradation by chemical or biological means produces various transition compounds. These transition compounds can be further transformed into valuable chemicals and biofuels that exhibit a wide range of applications and benefits. Recently, there has been a significant focus on this research area. Among the transition compounds, 5‐hydroxymethylfurfural (HMF), derived from the degradation of hexose, is an important biomass‐based platform compound that has hydroxymethyl and aldehyde functional groups in its molecular structure. This study reviews the recent progress in the transition metal‐catalysed conversion of HMF using Co and Mn to generate high‐value‐added downstream products. Furthermore, the active components, the carbon supporter, the reaction mechanism, the oxidants and the reaction conditions of the catalysts are discussed in detail. The oxidation of HMF deserves further research as an important and complete value‐added process for generating biomass‐based valuable chemicals.

This study aims to provide a comprehensive summary of the inactivation of airborne Escherichia coli [(E. coli), a gram-negative bacterium], Bacillus subtilis [(B. subtilis), a gram-positive bacterium], MS2 (a bacteriophage) virus, and Aspergillus versicolor [(A. versicolor), a fungus] with kinetic analysis utilizing microwave irradiation based on absorption material. The capacity of a microwave-absorbing material Fe₃O₄@SiC ceramic foam (Fe₃O₄@SiCcf) to inactivate bioaerosols when subjected to microwave (MW) irradiation (2450MHz) for 25 seconds at various output powers (750, 550, 350, and 150W) was determined. The airborne MS2 decreased by 4.5 logs at the microwave (MW) input energy density of 7.2 × 10³ kJ/m³, while that for E. coli was at around 4.4 logs, and that for B. subtilis was at 4.3 logs. The activation energy (Ea) applied was 13.2 kJ/mol (E. coli), 14.6 kJ/mol (B. subtilis), and that for MS2 virus was 9.6 kJ/mol. By contrast, this study has shown that A. versicolor log inactivation efficiency was lower and Ea was higher than others, which were 3.6 logs and 16.7 kJ/mol, respectively. In addition, MW - Fe₃O₄@SiCcf improved the inactivation efficiency of airborne microorganisms significantly compared with no absorbing material. Through the comparative analysis of energy consumption, the rate of constant airborne inactivation through MW irradiation is higher than UV and Fenton. However, the energy efficacy per MW irradiation order is lower. In summary, Fe₃O₄@SiCcf ceramic form is an energy-efficient material for inactivating airborne microorganisms under MW irradiation. Graphical Abstract

Antibiotic-resistant bacteria (ARBs) and antibiotic-resistant genes (ARGs) as new types of contaminants are discharged into the environment, increasing the risk of horizontal gene transfer (HGT). However, few researchers have examined the impacts of airborne ARB deactivation on HGT risk. The deactivation of airborne Escherichia coli 10667 (carrying sul genes) and the emission and removal of ARGs were mainly investigated in this study. Moreover, the potential mechanisms of HGT and transfer frequencies under microwave (MW) and ultraviolet (UV) irradiation were investigated using the nonresistant E. coli GMCC 13373 and E. coli DH5α with plasmid RP4 as the recipient and donor, respectively. E. coli CICC 10667 and E. coli DH5α with RP4 plasmid achieve log inactivation values as high as 5.5-log and 5.0-log, respectively, which were quite different from the antibiotic-sensitive strain E. coli CGMCC 13373 (3.4-log) subjected to MW irradiation. For UV disinfection, E. coli DH5α with the RP4 plasmid was reduced at 4.4-log, E. coli CGMCC 13373 was reduced at 2.3-log, and E. coli CICC 10667 was inactivated at 2.1-log. The removal rates of ARGs and HGT frequencies under MW irradiation were compared with those under UV irradiation. The ARGs removal efficiency (85.5%) obtained by MW was higher than that obtained by UV (48.2%). Consequently, the HGT frequency (0.008) of airborne ARGs released to the recipient (forward transfer) decreased and was lower than that under UV irradiation (0.014). Moreover, the plasmid RP4 was transferred from the donor to the surviving damaged E. coli 10667 as cell permeability (reverse transfer) was increased at a high HGT frequency (0.003) by MW, which was close to the value by UV (0.002). Additionally, sul1 and sul2 genes were confirmed to be more resistant to MW than the sul3 gene. These findings reveal the mechanism of HGT between damaged E. coli 10667 and surrounding environmental microbes. Microwave is a promising technology for disinfecting airborne microbes and preventing the spread of antibiotic resistance.