Excellent Catalytic Performance Research Articles

Fabrication of Laser-Induced Graphene on Carbon Electrodes for Efficient Hydrogen Evolution Reaction

Hierarchical porous carbon materials have received significant attention for application in catalytic water splitting because of their high efficiency, cost-effectiveness, and biocompatibility. In this study, laser-induced graphene (LIG) was fabricated on a carbon film- (CF-) type substrate for an efficient hydrogen evolution reaction (HER). The LIG-CF electrode was fabricated via laser-induced graphitization on a commercial polyimide (PI) film, followed by the pyrolysis of the LIG on the PI film (LIG-PI). During pyrolysis, the microscopic and material properties of the LIG remained intact, as verified through various characterizations. The as-prepared all-carbon electrode was then utilized as an electrode for the HER study in a 1.0 M KOH electrolyte and compared with LIG-PI and Pt electrodes. In the HER experiments, the optimized LIG-CF electrode exhibited excellent catalytic performance with zero-onset potential, and the potentials required to achieve high current densities of 10 and 20 mA/cm2 were 134 and 139 mV (vs. reversible hydrogen electrode (RHE)), respectively. The excellent performance of the LIG-CF electrode originates from the hierarchical porous structure of the LIG material, which serves as an electrochemically active site, and carbon substrate that facilitates the fast transport of ions at the electrode/electrolyte interface. Additionally, the carbon substrate shortens the transportation length of electrons which played a significant role for the enhanced performance of the LIG-CF electrode.

Engineering stable active Cu0-Cuσ+ sites via in situ surface reconstruction over Cu/CeO2 catalyst for the hydrogenation of carbon-oxygen bonds

Cu/CeO2 catalysts have been wildly used for the hydrogenation of carbon-oxygen bonds reactions due to their excellent catalytic performance. It is widely accepted that the Cu0-Cuσ+ interface could be the primary active sites during the reaction, but how to form and maintain highly dispersed such species remains challenging under the reaction conditions of high temperature and H2 partial pressure. In this work, we proposed an effective strategy to construct stable Cu0-Cuσ+ interface sites over the Cu/CeO2 catalysts by in situ N2O-involved oxidation treatment. It was evidenced that the sequential oxidation-reduction by N2O and H2 broke the grain boundaries of Cu nanoparticles and therefore facilitated the formation of the active Cu0-Cuσ+ sites, leading to an enhanced activity. However, a rapid deactivation was observed after this temporary enhancement due to the aggregation of copper species. We further introduced some additional cerium species during catalyst preparation. The 16Cu/CeO2-1Ce catalyst prepared by post-impregnation of 1 wt% cerium achieved a stable performance of 90.6% MA conversion after the N2O-involved oxidation treatment, which was much higher than that of 26.2% over the 16Cu/CeO2 catalyst. It was demonstrated that the strong interaction between the formed CeO2 and reconstructed Cu species prevented the metal sintering and increased the fraction of the Cu0-Cuσ+ sites. This method that combined in situ N2O-involved oxidation treatment and cerium modification may offer potential in engineering stable active sites for high-performance catalysts in the hydrogenation of carbon-oxygen bonds.

Carbonized cellulose microspheres loaded with Pd NPs as catalyst in p-nitrophenol reduction and Suzuki-Miyaura coupling reaction

Catalytic reduction of p-nitrophenol is usually carried out using transition metal nanoparticles such as gold, palladium, silver, and copper, especially palladium nanoparticles (Pd NPs), which are characterized by fast reaction rate, high turnover frequency, good selectivity, and high yield. However, the aggregation and precipitation of the metals lead to the decomposition of the catalyst, which results in a significant reduction of the catalytic activity. Therefore, the preparation of homogeneous stabilized palladium nanoparticles catalysts has been widely studied. Stabilized palladium nanoparticles mainly use synthetic polymers. Cellulose microspheres, as a natural polymer material with low-cost and porous fiber network structure, are excellent carriers for stabilizing metal nanoparticles. Cellulose microspheres impregnated with palladium metal nanoparticles were carbonized to have a larger specific surface area and highly dispersed palladium nanoparticles, which exhibited excellent catalytic activity in the catalytic reduction of p-nitrophenol. In this work, the cellulose carbon-based microspheres palladium (Pd@CCM) catalysts were designed and characterized by SEM, TEM, EDS, XRD, FTIR, XPS, TGA, BET, and so on. Furthermore, the catalytic performance of Pd@CCM catalysts was investigated via p-nitrophenol reduction, which showed high catalytic activity. This catalyst also exhibited excellent catalytic performance in the Suzuki-Miyaura coupling reaction. Linking aromatic monomer and benzene through Suzuki-Miyaura coupling was presented as an effective route to obtaining biaryls, and the synthesis method is low-cost and simple. In addition, Pd@CCM showed desirable recyclability while maintaining its catalytic activity even after five recycles. This work is highly suggestive of the design and application of the heterogeneous catalyst.

Roles of different Ni-Si interactions in methane combustion under oscillating temperature conditions

The silicon- modified nickel oxide catalysts with the same compositions but distinct Ni-Si interactions were obtained via different synthesis routes and utilized for methane combustion under conditions of oscillating temperatures. For catalysts prepared by co-grinding, amorphous SiO2 was dispersed on the surface of large NiO crystallites. During high-temperature calcination or reactions, the crystallization of SiO2, coupled with the sintering or decomposition of NiO crystallites, led to the inferior catalytic activity and stability. Interactions between Ni and Si species were enhanced in catalysts synthesized by precipitation. The Si species was incorporated into the NiO lattice to inhibit the growth of NiO crystallites and to generate nickel silicate species under thermal treatments. The small NiO crystallites provided more Ni3+ and active oxygen species for methane activation and oxidation, while the bulk nickel silicate species played a pivotal role in improving thermal stability, conjointly provoking excellent catalytic performance in cyclic heating–cooling tests between 180 and 800 °C. This study offers new insights into the design of metal oxide composites for catalytic applications.

Oxygen-vacancy-enriched MgO/carbon composite as a highly efficient electrocatalyst for phenazine/dihydrophenazine redox reaction of aqueous phenazine redox flow battery

Phenazine derivatives are attractive anolyte redox-active species in aqueous redox flow batteries (ARFBs). Unfortunately, they typically suffer from sluggish reaction kinetics, resulting in poor rate capability and inferior energy efficiency, especially under high current densities. Herein, we report a composite of MgO and Ketjen black carbon (MgO/KB) that can serve as a low-cost ARFB electrocatalyst to significantly improve the redox reaction kinetics of phenazine derivatives. The MgO/KB composite catalyst exhibits excellent catalytic performance, with an area-specific resistance (ASR) of 1.54 and 1.11 Ω/cm2 for the charge and discharge processes, respectively, as well as improved energy efficiency, capacity utilization, and durability in practical ARFB applications. Detailed research confirms that the oxygen vacancies within the MgO promote electron transfer and enhance catalytic activity for the electrochemical reaction of phenazine derivatives. Using density functional theory (DFT) calculations, we unveil that the underlying catalytic enhancement mechanism stems from a low free energy barrier of the rate-determining step (RDS) on oxygen-vacancy-enriched MgO for the oxidation reaction of dihydro-phenazine derivative. These findings will guide the design of highly active electrocatalysts for organic ARFBs.

Significantly improved dehydrogenation of dodecyl-N-ethylcarbazole over supported PdFe bimetallic nanocatalysts via polydopamine surface modification of Al2O3

N-ethylcarbazole (NEC) has great application prospects in hydrogen storage due to its ability to dehydrogenate at lower energy and high hydrogen storage performance. Developing supported metal catalysts with high catalytic activity and stability is key to achieving large-scale application of LOHC hydrogen storage technology. In this paper, bimetallic FePd/Al2O3@PDA-GR catalysts used for the dehydrogenation process of 12H-NEC were prepared by stepwise reduction methods, including chemical reduction and galvanic replacement, using PDA-coated Al2O3 as the support. The characterization results showed that adding PDA could anchor the metal particles, improve the dispersion of metal particles on the support surface, and reduce the agglomeration phenomenon. The nanoparticles of bimetallic catalysts prepared by the galvanic replacement were small, with the particle size distribution of 0.86 nm-2.78 nm, and an average size of 1.52 nm. The large number of exposed active sites enabled the catalysts to reduce the dosage of Pd while still possessing excellent catalytic performance. And part of Pd was coated on Fe NPs in the Fe5Pd1/Al2O3@PDA-GR catalysts prepared by galvanic replacement, which improved the atom utilization of Pd. And there is an obvious electronic interaction between Fe and Pd. In the dehydrogenation process of 12H-NEC to NEC, The prepared FePd/Al2O3@PDA-GR catalyst exhibited excellent catalytic performance and had a significantly greater dehydrogenation efficiency than found in the literature, 95% for 1 h and 100% for 3 h at 180 °C. The temperature drop to 160 °C did not affect the dehydrogenation efficiency, which remained at 98.1% for 3 h. The prepared catalyst had good stability, and the dehydrogenation efficiency was 93.1% after five successive cycles.

Ordered PtNiTiZrHf nanoparticles on carbon nanotubes catalyze hydrogen evolution reaction with high activity and durability

With the scarcity of the earth's natural resources, hydrogen production from electrolyzing water is seen as an alternative energy source. Although platinum (Pt) is an advanced catalyst for hydrogen evolution reaction (HER), its application is limited by high cost and limited electrocatalytic performance. In this article, the five-element alloy nanoparticles are successfully synthesized on carbon nanotubes (CNT) by employing liquid-phase reduction and gas-phase sintering to reduce Pt utilization and improve catalytic performance. For comparison, a series of ordered and disordered (PtNi)x(TiZrHf)100-x/CNT catalysts are obtained. Results show that the ordered samples have more excellent HER catalytic performance and stability than disordered samples in 0.5 M H2SO4 and 1 M KOH electrolytes. In particular, when the electrolyte is acidic, the overpotentials of ordered (PtNi)55(TiZrHf)45/CNT at 10 and 100 mA cm−2 are 11 and 52 mV, with low Tafel slope of 37.73 mV dec−1. At 10 mA cm−2, the stabilization time can reach 58 h, which is much better than commercial Pt/C (20 wt.%). Density functional theory (DFT) calculation shows that ordered (PtNi)55(TiZrHf)45/CNT has lower hydrogen adsorption energy and activated water adsorption energy than disordered one, indicating better performance in both acidic and alkaline electrolytes. It is mainly attributed to the electronic coupling effect after ordering that makes the overall D-band center decrease. This work presents a cost-effective approach to optimize the structural design for acid-base HER electrocatalysts.

Superior Catalytic Performance and Methanol Tolerance of Co@Mesoporous Graphene Nanocomposites toward Oxygen Reduction Reaction

AbstractThe global energy crisis and growing concerns about environmental pollution have spurred researchers to explore eco‐friendly methods of generating clean energy. Previous studies have often relied on noble metal catalysts to facilitate oxygen reduction reactions (ORR) in energy production reactions. However, their high cost has limited their widespread adoption, making the development of highly active and affordable ORR catalysts a significant challenge. In this study, a vacuum heat treatment technique was employed to fabricate a cobalt‐loaded mesoporous graphene (Co−Gs) nanocomposite. The inclusion of cobalt in graphene enhances the reaction, while the presence of mesoporous graphene provides a larger surface area to accommodate the active sites of Co. This synergistic effect promotes the improvement of catalytic performance. Additionally, the stability and methanol tolerance of Co−Gs nanocomposites is also superior than that of Pt−C. The excellent catalytic performance of the Co−Gs nanocomposite is attributed to a four‐electron pathway within the nanocomposite, as demonstrated by electrocatalytic kinetics investigations. Additionally, the interface interaction between the Co nanoparticles and Gs enhances the efficiency of electron transfer, effectively improving the catalytic performance. These findings highlight the potential of Co‐loaded graphene nanocomposites as highly efficient and cost‐effective electrocatalysts for clean energy application.

MIL-88A(Fe)/g-C3N4 composite and its catalytic membrane for tetracycline removal via peroxydisulfate activation: Performance, mechanism and toxicity evaluation

Heterogeneous catalyst/persulfate advanced oxidation process has been widely used in antibiotic wastewater treatment. As-designed MIL-88A(Fe)/g-C3N4 composite catalyst firstly activated peroxydisulfate (PDS) to degrade tetracycline (TC) in this work. Activating PDS by MIL-88A(Fe)/g-C3N4 has a higher efficiency and rate toward TC degradation compared with MIL-88A(Fe) and g-C3N4. After 60 min, the optimal MIL-88A(Fe)/g-C3N4-5 activated PDS to degrade about 80% of TC in water. The existence of g-C3N4 increases the specific surface area and active Fe2+ content of MIL-88(Fe), promotes PDS adsorption and utilization, thus showing an excellent catalytic performance for PDS activation. MIL-88A(Fe)/g-C3N4 activated PDS oxidation process synergistically removed TC by free radicals (O2•−, •OH and SO4•−) with non-free radicals (1O2), and the effect of some important operating factors on TC removal, the TC degradation pathways and toxicity of TC intermediates were analyzed. Moreover, the MIL-88A(Fe)/g-C3N4-5 powdered catalyst was designed into a catalytic membrane, which could remove 96% of TC in a short time (<10 min). The cycle tests confirm that powdered MIL-88A(Fe)/g-C3N4 composite catalyst and its catalytic membrane have a good recyclability and stability, demonstrating that this catalyst possesses a practical application potential in the treatment of TC polluted wastewater.

Tuning the crystallinity of the MnOx catalysts to promote toluene catalytic oxidation

ABSTRACT In this paper, the MnOx catalysts with excellent toluene oxidation performance were prepared by a simple precipitation method. The physicochemical properties of the prepared MnOx catalysts were investigated by XRD, BET, H2-TPR, O2-TPD and XPS. The obtained results revealed that the crystallinity of the prepared MnOx catalysts could be effectively regulated by changing the (NH4)2CO3/Mn(NO3)2 molar ratio, and thus affecting the oxygen vacancy concentration of the prepared MnOx catalysts. The prepared MnOx-4 catalyst with the (NH4)2CO3/Mn(NO3)2 molar ratio of 4.0 had the poor crystallinity and small grain size, which effectively promoted the oxygen defects in the MnOx catalyst to be formed. At the same time, the MnOx-4 catalyst had a large specific surface area, the highest low temperature reducibility and the largest number of oxygen vacancies and surface adsorbed oxygen species, which allowed more surface oxygen species to participate in the redox reaction, and promoted the toluene deep oxidation. Therefore, when the (NH4)2CO3/Mn(NO3)2 molar ratio was 4.0, the prepared MnOx-4 catalyst exhibited an excellent toluene catalytic oxidation performance and robust catalytic stability. What’s more, the toluene oxidation conversion on the MnOx-4 catalyst reached 99% at 230°C, and the MnOx-4 catalyst showed excellent resistance to water vapour.

The prediction of two-dimensional PbN: opened bandgap in heterostructure with CdO.

The development of two-dimensional (2D) materials has received wide attention as a generation of optoelectronics, thermoelectric, and other applications. In this study, a novel 2D material, PbN, is proposed as an elemental method using the prototype of a recent reported nitride (J. Phys. Chem. C 2023, 127, 43, 21,006-21014). Based on first-principle calculations, the PbN monolayer is investigated as stable at 900K, and the isotropic mechanical behavior is addressed by the Young's modulus and Poisson's ratio at 67.4Nm-1 and 0.15, respectively. The PbN monolayer also presents excellent catalytic performance with Gibbs free energy of 0.41eV. Zero bandgap is found for the PbN monolayer, and it can be opened at about 0.128eV by forming a heterostructure with CdO. Furthermore, the PbN/CdO is constructed by Van der Waals interaction, while the apparent potential drop and charge transfer are investigated at the interface. The PbN/CdO heterostructure also possesses excellent light absorption properties. The results provide theoretical guidance for the design of layered functional materials.

Activation of calcium sulfite by bismuth cobalt-copper perovskite-manganese dioxide composite for efficient degradation of metronidazole

The highly efficient BiCo0.5Cu0.5O3-MnO2 catalyst was prepared using the hydrothermal method and utilized for the first time to activate sulfite for degrading metronidazole (MNZ) in this study. Physicochemical analysis of the BiCo0.5Cu0.5O3-MnO2 catalyst was performed using XRD, FTIR, BET, SEM, TEM, and XPS, confirming the successful synthesis of catalyst. BiCo0.5Cu0.5O3-MnO2 demonstrated a larger specific surface area, a more uniform pore structure, and prevented perovskite agglomeration. The catalyst effectively activated CaSO3, resulting in the degradation of 99.94 % of MNZ within 30 min, showing excellent catalytic performance. Quenching experiments and EPR tests indicated that SO•-4, SO•-5 and 1O2 were the main reactive species, with the oxygen vacancy on the catalyst surface playing a crucial role in accelerating the formation of reactive species and electron transfer. Moreover, the valence transformation of Co, Cu, and Mn was identified as the main contributor to the activation of CaSO3, demonstrating significant synergistic effects. Liquid chromatography-mass spectrometry detected eleven intermediates, revealing that the BiCo0.5Cu0.5O3-MnO2/CaSO3 system could convert MNZ into low-toxicity products through three potential degradation pathways. Density functional theory (DFT) calculations showed that higher Fukui indices of MNZ sites were more susceptible to free radical attack. The BiCo0.5Cu0.5O3-MnO2/CaSO3 system also exhibited excellent degradability to different natural water bodies and other pollutants. Furthermore, the catalyst displayed strong stability and outstanding catalytic performance after 5 cycles. This study presents a versatile strategy for developing highly efficient green catalysts, which could be utilized in organic wastewater treatment.

Boosting electrocatalytic nitrogen fixation on Ni-P codoped MoS2 nanosheets

Electrocatalytic nitrogen fixation in an aqueous solution is considered a promising approach to ammonia synthesis. Still, this process has low Faraday efficiency and ammonia yield, so it is necessary to develop an efficient, clean, and safe catalyst to promote nitrogen reduction process. Doping can be easily carried out during the crystal growth owing to the weak interaction between the sandwiched layers (due to van der Waals forces) of MoS2. Here, a Ni-P codoped MoS2 nanosheets is designed as a highly efficient catalyst for electrochemical nitrogen fixation with superior selectivity. Especially, the doping of Ni achieved the transformation of MoS2 from 2 H phase to 1 T phase, improving the conductivity of the material. In addition, the doping of P creates more sulfur vacancies in the catalyst, thereby producing more H*, which promotes the adsorption and activation of nitrogen. The as-synthesized Ni-P codoped MoS2 nanosheets show excellent catalytic performance with a high yield of electrocatalytic ammonia synthesis (84.29 μgNH3 h−1 mgcat−1) and Faraday efficiency (2.39 %) at −0.5 V versus reversible hydrogen electrode in acidic electrolytes (0.005 M H2SO4), which outperformed most electrocatalytic ammonia synthesis catalysts. Furthermore, the Ni-P codoped MoS2 catalyst also shows outstanding electrochemical stability and durability. This work may offer a hopeful lead for designing effective non-noble-metal NRR electrocatalysts.

An enzymatic continuous-flow reactor based on a pore-size matching nano- and isoporous block copolymer membrane

Continuous-flow biocatalysis utilizing immobilized enzymes emerged as a sustainable route for chemical synthesis. However, inadequate biocatalytic efficiency from current flow reactors, caused by non-productive enzyme immobilization or enzyme-carrier mismatches in size, hampers its widespread application. Here, we demonstrate a general-applicable and robust approach for the fabrication of a high-performance enzymatic continuous-flow reactor via integrating well-designed scalable isoporous block copolymer (BCP) membranes as carriers with an oriented and productive immobilization employing material binding peptides (MBP). Densely packed uniform enzyme-matched nanochannels of well-designed BCP membranes endow the desired nanoconfined environments towards a productive immobilized phytase. Tuning nanochannel properties can further regulate the complex reaction process and fortify the catalytic performance. The synergistic design of enzyme-matched carriers and efficient enzyme immobilization empowers an excellent catalytic performance with >1 month operational stability, superior productivity, and a high space-time yield (1.05 × 105 g L−1 d−1) via a single-pass continuous-flow process. The obtained performance makes the designed nano- and isoporous block copolymer membrane reactor highly attractive for industrial applications.

Electron-Rich Ru Supported on N-Doped Coffee Biochar for Selective Reductive Amination of Furfural to Furfurylamine.

Highly selective synthesis of primary amines from renewable biomass has attracted increasing attention, but it still faces great challenges in chemical industry applications. In this study, an electron-rich Ru catalyst was constructed by doping N into coffee biochar using a one-pot carbonization method (Ru/NCB-600). Ru/NCB-600 showed high catalytic activity and yield for the reductive amination of furfural with green and cheap NH3 and H2. The excellent catalytic performance of Ru/NCB-600 was closely correlated to the formation of electron-rich Ruδ- species (Ruδ--Nxδ+), which endowed Ru/NCB-600 with an enhanced H2 adsorption and activation ability. Ru/NCB-600 showed a high formation rate of 95.6 gfurfurylamine·gRu-1·h-1 and a high yield of furfurylamine (98.6%) at 50 °C. Ru/NCB-600 can also be used for the reductive amination of various carbonyl compounds in good to excellent yield (95.4-99%). This study thus provides a potential pathway for the highly selective reductive amination of carbonyl compounds by regulating the electron density of Ru.

Sulfur doped Co3O4 catalyst for efficient and stable oxygen evolution reaction at high current density

The development of oxygen evolution reaction (OER) electrocatalysts with excellent stability at high current density is key to achieving efficient hydrogen production, and spinel Co3O4 is a promising alternative material, yet its application to high current density remains challenging. Here, we employ doping engineering to apply Co3O4 modified by S to the OER. The doping of S optimizes the electronic environment of Co and generates richer oxygen defects, leading to excellent catalytic performance and cycling stability at high current density. The best performing S–Co3O4-45@NF catalyst that required 265 mV to achieve 10 mA/cm2. Furthermore, it exhibits outstanding cycling durability at 10, 200 and 1200 mA/cm2 as well as excellent mass transfer performance in multi-step current tests. The present work provides ideas for the development of low-cost and efficient transition metal-based electrocatalysts at high current density.

Synergistic effect of Ni and CeOx in NiCeOx/SSZ-13 catalyst for boosting activity and stability during dry reforming of methane

The stability of industrial catalysts for dry reforming of methane (DRM) reaction is still an urgent challenge. The multifunctional nanocatalyst of SSZ-13 supported Ni/CeOx bimetallic catalysts was successfully fabricated by the impregnation method. The Ni/CeOx species was dispersed highly in the microporous structure of SSZ-13, and the Ni active sites can activate the C-H bond dissociation of CH4, while the oxygen vacancy could promote the adsorption and activation of CO2. The NiCeOx/SSZ-13 catalyst showed excellent catalytic performance for dry reforming of methane, i.e., its conversion of CH4 and CO2 were 91 and 94%, and the ratio of H2/CO was about 0.88 at 750 °C after 50 h. Based on the results of CH4&CO2-TPSR and NH3-TPD, the synergy effect of NiCeOx species can promote the adsorption and activation of CH4 and CO2, and the coke on the surface during DRM is readily converted to CO by reacting with the surface oxygen from CeOx species, which effectively boost the elimination of carbon deposits. It highlights a new strategy for the fabrication of high-efficient zeolite catalysts for DRM to enhance the utilization of CH4 and CO2.

Sublayer-Sulfur-Vacancy-Induced Charge Redistribution of FeCuS Nanoflower Awakening Alkaline Hydrogen Evolution.

Advancing the progress of sustainable and green energy technologies requires the improvement of valid electrocatalysts for the hydrogen evolution reaction (HER). Reconfiguring charge distribution through heteroatom doping-induced vacancy serves as an effective approach to implement high performance for HER catalysts. Here, we successfully fabricated Fe-doped CuS (FeCuS) with the sublayer sulfur vacancy to judge its HER performance and dissect the activity origins. Density functional theory calculation further elucidates that the primary factor contributing to the heightened HER activity is that the sublayer sulfur vacancies awaken the charge redistribution. In addition to effectively decreasing the energy barrier associated with the Volmer step, it modulates the adsorption/desorption capacity of H*. As a result, its intrinsic activity for the HER has significantly increased. Concretely, the obtained FeCuS displays an excellent catalytic performance, whose Tafel slope is only 59 mV dec-1 and the overpotential (at 10 mA cm-2) is as low as 71 mV in an alkaline environment, surpassing the majority of previously documented catalysts in scientific literature. This work shows that the construction of sublayer sulfur vacancies by Fe doping can achieve the charge redistribution and precise tuning of electronic structure; thereby, the inert CuS can be transformed into highly efficient electrocatalysts.

Nitrogen-Doped Biochar for Enhanced Peroxymonosulfate Activation to Degrade Phenol through Both Free Radical and Direct Oxidation Based on Electron Transfer Pathways.

Nowadays, super nitrogen-doped biochar (SNBC) material has become one of the most promising metal-free catalysts for activating peroxymonosulfate (PMS) to degrade organic pollutants. To understand the evolution of SNBC properties with fabrication conditions, a variety of SNBC materials were prepared and characterized by elemental analysis, N2 adsorption-desorption, scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. We systematically investigated the activation potential of these SNBC materials for PMS to degrade phenol. SN1BC-800 with the best catalytic performance was obtained by changing the activation temperatures and the ratio of biochar to melamine. The effects of catalyst dosage, the PMS concentration, pH, and reaction temperature on phenol degradation were studied in detail. In the presence of 0.3 g/L SN1BC-800 and 1 g/L PMS, the removal rate of 20 mg/L phenol could reach 100% within 5 min. According to electron paramagnetic resonance spectra and free radical quenching experiments, a nonfree radical pathway of phenol degradation dominated by 1O2 and electron transfer was proposed. More interestingly, the excellent catalytic performance of the SN1BC-800/PMS system is universally applicable in the degradation of other typical organic pollutants. In addition, the degradation rate of phenol is still over 80% after five reuses, which shows that the SN1BC-800 catalyst has high stability and good application prospects in environmental remediation.

Cooperative effect of NHPI and BmimBr for promoting cumene catalytic oxidation

Cumyl hydroperoxide (CHP) is an important intermediate in phenol/acetone production; however, its long reaction time and low yield remain industrial challenges. In this study, an active and promising catalyst combination—NHPI + BmimBr ionic liquid (IL)—was developed for cumene oxidation under solvent-, transition-metal-salt-, and CHP-initiator-free conditions, which exhibited a synergistic catalytic effect and excellent catalytic performance. The cumene oxidation rate was accelerated by 33.3 %, leading to the rapid synthesis of a significant amount of the target product, CHP. DFT calculations demonstrated that NHPI undergoes hydrogen atom abstraction reaction through its interaction with BmimBr, forming PINO and carbene-Br radicals that can extract hydrogen. Additionally, EPR analysis demonstrated that both radicals are involved in the reaction. The nature of the synergistic effect was confirmed using theoretical and experimental approaches. The proposed catalyst eliminates the requirement of an initiator for IL and NHPI application, paving the way for the efficient production of CHP without solvents or initiators.