Excellent Catalytic Activity Research Articles

Co/CoSe heterojunction as bifunctional oxygen electrocatalysts for rechargeable Zinc–Air batteries

The construction of suitable heterostructures in materials can tune the Fermi energy levels and electron transport rates of materials to achieve attractive oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) properties. In this study, a catalyst anchored in nitrogen-doped carbon nanowires (NCNW) with a heterogeneous interface of Co and CoSe is constructed to realize high-performance ORR and OER bifunctional catalysis. These Co and CoSe heterostructure interfaces can optimize the adsorption of intermediates. The Co/CoSe@NCNW catalyst performs excellent ORR catalytic activity (E1/2 = 0.89 V), and good OER activity (potential at 10 mA/cm2, Ej = 10 = 1.55 V). More importantly, the material shows excellent performance in rechargeable zinc-air batteries (ZABs). The open-circuit voltages of 1.47 and 1.50 V and the peak power densities of 122.56 and 74.49 mW/cm2 in liquid and solid electrolytes, respectively, are superior to those of the ZABs prepared from noble metals. Consequently, the construction of heterogeneous structures can convincingly boost the commercialization of rechargeable ZABs, and be extended to other fields involving ORR and OER.

Atomically Engineered Defect-Rich Palladium Metallene for High-Performance Alkaline Oxygen Reduction Electrocatalysis.

Defect engineering is a key chemical tool to modulate the electronic structure and reactivity of nanostructured catalysts. Here, it is reported how targeted introduction of defect sites in a 2D palladium metallene nanostructure results in a highly active catalyst for the alkaline oxygen reduction reaction (ORR). A defect-rich WOx and MoOx modified Pd metallene (denoted: D-Pd M) is synthesized by a facile and scalable approach. Detailed structural analyses reveal the presence of three distinct atomic-level defects, that are pores, concave surfaces, and surface-anchored individual WOx and MoOx sites. Mechanistic studies reveal that these defects result in excellent catalytic ORR activity (half-wave potential 0.93V vs. RHE, mass activity 1.3AmgPd-1 at 0.9 V vs. RHE), outperforming the commercial references Pt/C and Pd/C by factors of ≈7 and ≈4, respectively. The practical usage of the compound is demonstrated by integration into a custom-built Zn-air battery. At low D-Pd M loading (26µgPdcm-2), the system achieves high specific capacity (809mAhgZn -1) and shows excellent discharge potential stability. This study therefore provides a blueprint for the molecular design of defect sites in 2D metallene nanostructures for advanced energy technology applications.

Morphological regulation of Pt/CeO2 and its catalytic dehydrogenation of methylcyclohexane in fixed bed reactor

A series of Pt/CeO2 compounds with hollow spheres (Pt/CeO2–S), wires (Pt/CeO2–W), and particle (Pt/CeO2–P) morphologies were prepared and further used for catalytic liquid organic hydrogen carrier (LOHC) dehydrogenation. The exposure and distribution of different crystal faces affected the nucleation process of crystals and then formed different microscopic morphologies. Compared with Pt/CeO2–W and Pt/CeO2–P, Pt/CeO2–S showed hollow spherical structures with significantly higher oxygen vacancy concentrations and specific surface areas. These structural differences not only affected platinum (Pt) dispersion, but also affected the activity and stability of the catalyst, thus promoting methylcyclohexane (MCH) conversion. The fixed bed reaction showed that Pt/CeO2–S had excellent catalytic activity, with the MCH conversion rate at 97.7 % and hydrogen release rate of 350.50 mmol/g(Pt)/min, and it still maintained stable activity after 72 h. Under the same conditions, the MCH conversion rates for Pt/CeO2–W and Pt/CeO2–P were only 77.23 % and 32.02 %, respectively. Therefore, through the growth pattern and morphology controls of catalyst supports, this was an effective means for improving the dehydrogenation performance of LOHC.

Enhanced selectivity in the production of furans/olefins through ex-situ catalytic pyrolysis over metal-modified TS-1

Catalytic pyrolysis technology is one of the most environmental and efficient approach in converting biomass waste into high-value chemicals and fuels. In this study, the ex-situ catalytic pyrolysis of cellulose to produce furans and olefins was reported using various metal-loaded TS-1 as catalysts. The experimental results showed that the Au/TS-1 exhibited an exceptional catalytic activity in the production of furans and olefins, achieving a selectivity of 49.17 % and 40.65 %, respectively. Ni/TS-1 effectively promoted the formation of ethylene, yielding a selectivity of 97.49 % and a yield of 6.11 C-mol%. Under the optimized conditions: pyrolysis temperature of 550 ℃, catalytic temperature of 600 ℃, and catalyst to cellulose mass ratio of 20:1, the Au/TS-1 catalyst achieved a furans selectivity of 41.91 % with a yield of 11.94 C-mol%, while olefins selectivity and yield were 49.84 % and 18.99 C-mol%, respectively. At this condition, Au/TS-1 still has excellent catalytic activity after 10 cycles and has good catalytic effect towards different biomass feedstocks. Furthermore, the possible mechanism to produce furans and olefins was revealed. This research offers valuable insights for guiding the directed conversion of biomass into value-added chemicals, paving the way for a more sustainable future.

Laccase-mimicking activity of octahedral Mn3O4 nanoparticles and fluorescence of carbon dots as dual-mode signals for the specific detection of arsenic(V) in environmental water samples

The detrimental growth of water pollutants such as heavy metals has become a life-threatening problem in the modern era. Challenges remain in the development of rapid and accurate methods for detecting pentavalent arsenic [As(V)] in environmental water. The octahedral Mn3O4 nanoparticles (NPs) did not display excellent laccase-mimicking catalytic activity, whereas the adsorbed As(V) on the surface significantly enhanced the catalytic activity. Meanwhile, the quinone imine generated from the substrates 2,4-dichlorophenol (2,4-DP) and 4-aminoantipyrine (4-AAP) catalyzed by octahedral Mn3O4 NPs further quenched the carbon dots fluorescence. Thus, it is possible to establish a fast and accurate dual-mode sensor for detecting As(V). The developed dual-mode method of As(V) detection has good sensitivity and selectivity. The limit of detection for As(V) in colorimetric mode is 6.96 μg·L−1, whereas in the fluorescent mode, it is as low as 2.56 μg·L−1. Moreover, the detection data obtained by the dual-mode method can be validated by each other, thereby ensuring the dependability of the sensing system. The constructed dual-mode method with merits of sensitivity, speed and accuracy can offer a powerful tool for As(V) detection in environmental water. Furthermore, the application of laccase-mimicking activity in dual-mode detection provides new strategies for other environmental hazard detection.

In-Situ investigation of the catalytic hydrogenation reaction of 4-nitrothiophenol by using single Pt@Au nanowires as a new platform

Investigating the kinetics and mechanisms of catalytic hydrogenation reaction is important for fundamental research and chemical engineering, especially at single nanowire/nanoparticle level. In this work, we constructed a dual-functional single Pt@Au nanowire (Pt@Au NW) reaction platform, which was used for in-situ monitoring the p-nitrothiophenol (4-NTP) catalytic reduction process by using surface-enhanced Raman scattering (SERS) and UV–vis spectroscopy. The conversion of reactants and intermediates as well as the product generation during the reaction process were analyzed carefully, and the influencing factors of temperature and light were also discussed. Moreover, the density functional theory (DFT) was used to further investigate the effect of the single Pt@Au NW on catalytic hydrogenation reaction of 4-NTP. The results show that the single Pt@Au NW can be a good platform for in-situ monitoring catalytic hydrogenation reaction of 4-NTP with excellent catalytic activity, high stability, and good reproducibility, and clarified that trans-dimercaptoazobenzene (trans-DMAB) intermediates were produced that are further converted to the p-aminothiophenol (4-ATP). The work will not only give researchers new insights into the combination of the single nanowire/nanoparticle with spectroscopic techniques, but may also inspire further in-depth studies of multifunctional catalysts for catalytic hydrogenation reaction at single entity level.

Simple generic self-assembly fabrication of transition metal borates on polyaminophenylboric acid modified foam nickel for highly-efficient overall water splitting

Water electrocatalysis for hydrogen production as a prospect strategy to store renewable energy and reduce carbon emissions has attracted great attention, and exploring water electrolysis catalysts has become a research hotspot for widespread industrial water electrolysis application. Very recently, transition metal borates have been demonstrated great potential for electrocatalytic hydrogen or oxygen evolution in alkaline media. However, a generic method for fabricating transition metal borates as bifunctional oxygen catalysts are still challenging. Herein, through a two-step process including poly-aminophenylboronic acid electrodeposition and subsequent electrostatic self-assembly of transitional metal ions, for the first time, to our best knowledge, a simple and generic approach to fabricate polyaminophenylborate transition metal salt modified nickel foam electrodes (PAB-M/NF, M represents transition metal element) was developed for highly efficient water splitting. As a proof of concept, the obtained PAB-Ru/NF exhibited remarkable bifunctional HER and OER catalytic activities and stability in alkaline medium. To drive the HER and OER with a current density of 10 mA cm−2 in 1 M KOH electrolyte, PAB-Ru/NF only required an overpotential of 14 mV and 301 mV, respectively. Moreover, even at a great current density of 250 mA cm−2, PAB-Ru/NF can exhibit very favorable long-term stability for over 35 h. When assembled into an electrolyzer with PAB-Ru/NF as both the anode and cathode, a current density of 10 mA cm−2 can be achieved at a very low cell voltage of 1.50 V. In addition, the other PAB-M/NF catalysts (M including but not limited to Fe, Co and Ni) prepared by the same way also show excellent bifunctional HER and OER catalytic activities and durability. This study provides a prospective and economically feasible generic approach for developing practical bifunctional catalysts for industrial water electrolysis.

Small Organic Molecule‐Assisted Mesoscopic Self‐Assembly of SnO2 Nanoparticles: An Efficient Catalyst for the Synthesis of β‐Nitroaldol

AbstractOver the past few decades, huge number of mesoporous materials have been synthesized by using supramolecular assembly of ionic/non‐ionic surfactants as structure‐directing agents (SDAs). Here, we report a facile synthetic strategy to fabricate self‐assembled SnO2 nanoparticles with well‐defined nanocrystalline spherical morphology and mesoporosity using sodium salicylate as a SDA and stabilizing agent. The mesophases of the materials were investigated by powder X‐ray diffraction, TEM and N2 sorption studies. TEM results show that the mesopores are formed by the assembly of ultrasmall SnO2 NPs with broad range of interparticle voids and N2 sorption studies agreed well with this TEM data. This synthesis strategy facilitated the generation of SnO2 NPs with increased surface area and pores of nanoscale dimensions with a large number of exposed surface‐active sites. The photoinduced electron transfer in these materials was investigated by the fluorescence quenching study with pyranine, which suggested the presence of surface Lewis basicity. The materials showed excellent catalytic activity for the synthesis of β‐nitroaldol through the reaction of benzaldehyde and nitromethane. The heterogeneous nature of the catalyst could be attributed to the high surface area, presence of numerous surface active sites, and structural robustness of the self‐assembled SnO2 nanostructure. The catalysts exhibited negligible loss in activity after several catalytic cycles.

Enhanced Electrocatalytic Performance of the FePt/PPy-C Composite toward Methanol Oxidation.

A novel FePt/PPy-C composite nanomaterial has been designed and investigated as a methanol oxidation reaction (MOR) electrocatalyst. The FePt nanoparticles with an average diameter of about 3 nm have been prepared by the co-reduction method and then loaded onto the PPy-C composite support. The electrocatalytic performance is affected by the composition of the FePt nanoparticles. The experimental results indicated that the Fe1.5Pt1/PPy-C catalyst exhibited excellent catalytic activity and stability for MOR, with mass activity and specific activity of 1.76 A mgPt-1 and 2.71 mA cm-2, respectively, which are 5.18 and 4.60 times higher than that of the commercial Pt/C catalyst. Density functional theory (DFT) has been employed to simulate the electrical structures of catalyst supports, and the mechanism of the methanol oxidation process has been further analyzed. The heterojunctions of the PPy-C interface could accelerate the electron migration from the electrocatalytic center to the electrodes. The possibility of methanol oxidation has been improved effectively, which can be confirmed by the d-band center and CO adsorption energy on FePt nanoparticles in the DFT calculation results.

Oxygen vacancy–rich K-Mn3O4@CeO2 catalyst for efficient oxidation degradation of formaldehyde at near room temperature

Synthesis of catalysts with high catalytic degradation activity for formaldehyde (HCHO) at room temperature is highly desirable for indoor air quality control. Herein, a novel K-Mn3O4@CeO2 catalyst with excellent catalytic oxidation activity toward HCHO at near room temperature was reported. In particular, the K addition in K-Mn3O4@CeO2 considerably enhanced the oxidation activity, and importantly, 99.3 % conversion of 10 mL of a 40 mg/L HCHO solution at 30 °C for 14 h was achieved, with simultaneous strong cycling stability. Moreover, the addition of K species considerably influenced the chemical valence state of Mn from +4 (ε-MnO2) to +8/3 (Mn3O4) on the surface of CeO2, which obviously changed the tunnel structure and the number of oxygen vacancies. One part of K species is uniformly dispersed on K-Mn3O4@CeO2, and the other part exists in the tunnel structure of Mn3O4@CeO2, which is mainly used to balance the negative charge of the tunnel and prevent collapse of the structure, providing enough active sites for the catalytic oxidation of HCHO. We observed a phase transition from tunneled KMnO2 to Mn3O4 to tunneled MnO2 with the decreasing K+ content, in which K-Mn3O4@CeO2 exhibited higher HCHO oxidation activity. In addition, K-Mn3O4@CeO2 exhibited lower oxygen vacancy formation and HCHO adsorption energies in aqueous solution based on density functional theory calculations. This is because the K species provide more active oxygen species and richer oxygen vacancies on the surface of K-Mn3O4@CeO2, promote the mobility of lattice oxygen and the room-temperature reduction properties of oxygen species, and enhance the ability of the catalyst to replenish the consumed oxygen species. Finally, a possible HCHO catalytic oxidation pathway on the surface of K-Mn3O4@CeO2 catalyst is proposed.

Nanoarchitectonics of hollow Co3O4 through tannic acid etching of ZIF-67 for catalysis of toluene oxidation

Oxide catalysts obtained by derivatization of MOFs as precursors often have excellent results in the catalysis of VOCs. In this study, the Co3O4 catalysts obtained by pyrolysis after tannic acid etching using ZIF-67 as precursor showed excellent toluene catalytic activity. Among them, Co3O4 −1–15 showed the best catalytic activity with T90 = 219 °C (the conversion temperatures of 90 %), which was 20 °C lower than that of Co3O4 -O obtained by direct pyrolysis of ZIF-67. It also exhibits excellent stability and cyclic stability. After tannic acid treatment, Co3O4 −1–15 exposed higher surface Co3+ and Olatt (surface lattice oxygen) content, which were the key factors for its most outstanding catalytic activity. Lattice oxygen mobility and oxygen vacancies were also important factors affecting catalyst activity.

Engineering Zeolitic-Imidazolate-Framework-Derived Mo-Doped Cobalt Phosphide for Efficient OER Catalysts.

Designing a cheap, competent, and durable catalyst for the oxygen evolution reaction (OER) is exceedingly necessary for generating oxygen through a water-splitting reaction. In this project, we have designed a ZIF-67-originated molybdenum-doped cobalt phosphide (CoP) using a simplistic dissolution-regrowth method using Na2MoO4 and a subsequent phosphidation process. This leads to the formation of an exceptional hollow nanocage morphology that is useful for enhanced catalytic activity. Metal-organic frameworks, especially ZIF-67, can be used both as a template and as a metal (cobalt) precursor. Molybdenum-doped CoP was fabricated through a two-step synthesis process, and the fabricated Mo-doped CoP showed excellent catalytic activity during the OER with a lower value of overpotential. Furthermore, the effect of the Mo amount on the catalytic activity has been explored. The best catalyst (CoMoP-2) showed an onset potential of around 1.49 V at 10 mA cm-2 to give rise to a Tafel slope of 62.1 mV dec-1. The improved catalytic activity can be attributed to the increased porosity and surface area of the resultant catalyst.

In-situ construction of integrated transition metals and metal oxides with carbon nanomaterial heterostructures to modulate electron redistribution for boosted water splitting

Heterostructure engineering has been proposed as a promising approach to construct high-efficiency bifunctional electrocatalyst for overall water splitting. Integrated transition metal and metal oxide heterointerfaces with carbon nanomaterials are designed to facilitate electrocatalytic performance toward overall water splitting. Fe/MnO heterostructures are fabricated on graphene using a one-step DC arc plasma technology. In this way, increased electrochemically active specific areas, accelerated charge transfer, and proper interfacial electronic structure can be achieved. Benefiting from the synergistic effect of multiple materials, fabricated Fe/MnO/graphene heterointerfaces can make the redistribution of electrons between heterointerfaces, which effectively optimizes adsorption/desorption energy of the reaction intermediates. Fe/MnO/graphene delivers excellent catalytic activity with only 362 mV and 339 mV overpotential to reach current density of 10 mA cm−2 for OER and HER and exceptional long-term stability in alkaline solution. As electrocatalyst at both the cathode and the anode of an alkaline electrolyzer simultaneously, Fe/MnO/graphene electrocatalyst requires a cell voltage of 1.987 V at a current density of 10 mA cm−2 for overall water splitting. Therefore, this work offers a feasible route to construct hierarchically nanohybrids as bifunctional electrocatalysts by combining transition metal and metal oxide with carbon nanomaterials.

Introducing Platinum Cryoaerogel As a Low Loading Cathode Catalyst in PEM Water Electrolysis

An important cost factor for polymer electrolyte membrane water electrolysers is precious metals as the catalyst layers. Therefore, reducing of the platinum loading on the cathode side and the iridium on the anode is essential to reduce the overall costs of hydrogen production. Cryoaerogels from noble metal nanoparticles are a suitable, yet unexplored material for use as a catalyst in water electrolysis. They combine high porosity and surface area with an excellent catalytic activity at low loadings of noble metal.[1] Recently, we have succeeded in producing a carbon-based gas diffusion electrode (GDE) coated with platinum cryoaerogel as the catalyst. The mechanical connection to the carbon underneath as well as maintaining a high protonic conductivity in contact to the Nafion membrane allowed the application to the water electrolysis cell. The manufacturing includes an oven treatment, whose temperature is particularly decisive for the structure of the cryoaerogel. Figure 1 left shows the polarization curves of the samples pyrolyzed at 300°C, 350°C and 500°C compared to a commercial GDE (platinum loading of 0.5 mg/cm²). All measurements are repeated three times and showed good reproducibility, as indicated by the error bars on the graph. Among the different temperatures, 300°C is the optimum for the pyrolysis process as it showed the lowest voltages. The catalytic performance of the different samples can be correlated to the micro-structure of the cryoaerogel layer represented by the SEM images and the electronic-structure of the platinum as shown by X-ray photoelectron spectroscopy (XPS). Although in figure 1 the performance of the cryoaerogel catalyst layers is not better than the commercial GDE, however, the platinum loading is significantly reduced by 70% (0.15 mg/cm2). Moreover, the reproducibility of the measurements proofs the possibility of using cryoaerogels in the full water electrolysis cell.[1] Müller, D., Zámbó, D., Dorfs, D., Bigall, N. C., Cryoaerogels and Cryohydrogels as Efficient Electrocatalysts. Small 2021, 17, 2007908. https://doi.org/10.1002/smll.202007908 Figure 1

Electroless plating-acid etching strategy to synthesize Co–Fe–Mn–P nanosheet arrays bifunctional catalyst for efficient water splitting

Simple and efficient preparation of highly active electrocatalysts is of great significance for water splitting. Herein, Co–Fe–Mn–P/NF electrode was prepared on a nickel foam through electroless plating-acid etching strategy, which showed excellent bifunctional catalytic activity for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1 M KOH. For HER, only 13 and 78 mV overpotentials are needed to reach current densities of 10 and 100 mA cm−2 with Tafel slopes as low as 33.7 mV dec−1. While for OER, the Co–Fe–Mn–P/NF required small overpotentials of 275 and 327 mV to reach the current densities of 10 and 100 mA cm−2, and the Tafel slope is only 34.8 mV dec−1. In addition, Co–Fe–Mn–P/NF only needs 1.562 V to drive water splitting to produce a current density of 10 mA cm−2. Furthermore, it also demonstrated excellent stability by maintaining stable operation for more than 24 h.

High-entropy-perovskite subnanowires for photoelectrocatalytic coupling of methane to acetic acid

The incorporation of multiple immiscible metals in high-entropy oxides can create the unconventional coordination environment of catalytic active sites, while the high formation temperature of high-entropy oxides results in bulk materials with low specific surface areas. Here we develop the high-entropy LaMnO3-type perovskite-polyoxometalate subnanowire heterostructures with periodically aligned high-entropy LaMnO3 oxides and polyoxometalate under a significantly reduced temperature of 100 oC, which is much lower than the temperature required by state-of-the-art calcination methods for synthesizing high-entropy oxides. The high-entropy LaMnO3-polyoxometalate subnanowires exhibit excellent catalytic activity for the photoelectrochemical coupling of methane into acetic acid under mild conditions (1 bar, 25 oC), with a high productivity (up to 4.45 mmol g‒1cat h‒1) and selectivity ( > 99%). Due to the electron delocalization at the subnanometer scale, the contiguous active sites of high-entropy LaMnO3 and polyoxometalate in the heterostructure can efficiently activate C − H bonds and stabilize the resulted *COOH intermediates, which benefits the in situ coupling of *CH3 and *COOH into acetic acid.

Solid electrochemiluminescence sensor by immobilization luminol in Zn-Co-ZIF CNFs for sensitive detection of procymidone in vegetables.

Asolid-state electrochemiluminescence (ECL) sensor was fabricated by immobilizing luminol, a classical luminescent reagent, on a Zn-Co-ZIF carbon fiber-modified electrode for the rapid and sensitive detection of procymidone (PCM) in vegetable samples. The sensor was created by sequentially modifying the glassy carbon electrode with Zn-Co-ZIF carbon fiber (Zn-Co-ZIF CNFs), Pt@Au NPs, and luminol. Zn-Co-ZIF CNFs, prepared through electrospinning and high-temperature pyrolysis, possessed a large specific surface area and porosity, making it suitable as carrier and electron transfer accelerator in the system. Pt@Au NPs demonstrated excellent catalytic activity, effectively enhancing the generation of active substances. The ECL signal was significantly amplified by the combination of Zn-Co-ZIF CNFs and Pt@Au NPs, which can subsequently be diminished by procymidone. The ECL intensity decreased proportionally with the addition of procymidone, displaying a linear relationship within the concentration range 1.0 × 10-13 to 1.0 × 10-6 mol L-1 (R2 = 0.993). The sensor exhibited a detection limit of 3.3 × 10-14 mol L-1 (S/N = 3) and demonstrated outstanding reproducibility and stability, making it well-suited for the detection of procymidone in vegetable samples.

Carbon cloth supporting (CrMnFeCoCu)3O4 high entropy oxide as electrocatalyst for efficient oxygen evolution reactions

High-entropy oxides (HEOs) have received more attentions for the oxygen evolution reaction (OER) due to their rich active sites and high configurational entropy. However, the difficulty of electron transfer during the catalysis process limits the application of HEOs in OER catalysis. Herein, we proposed the carbon cloth (CC) supporting (CrMnFeCoCu)3O4 HEO with spinel structure synthesized by the hydrothermal method following with the calcination. The carbon cloth used as the support of HEO could improve the conductivity and stability of the catalyst. Meanwhile, the excellent catalytic activity of HEO with the synergistic effects of multiple metal elements would be maintained. And the homo-disperse HEO nanoparticles were exposed on the surface carbon fibers, which was conducive to contact with electrolyte. Based on the above merits, the intrinsic catalytic activity of (CrMnFeCoCu)3O4/CC was enhanced, which was attributed to the self-regulating electronic structure and the fine HEO nanoparticles exposed on the surface of catalysts. And the catalytic kinetic process of (CrMnFeCoCu)3O4/CC was accelerated, mainly due to its conductivity and richer oxygen vacancies. The (CrMnFeCoCu)3O4/CC exhibited the outstanding OER performance with an ultralow overpotential (210.8 mV @10 mA·cm−2), a smaller Tafel slope value (59.4 mV·dec−1), and super long-term durability, which was competitive with other transition metal oxides based catalysts and noble metal oxides. Therefore, the excellent OER performance implied that the (CrMnFeCoCu)3O4/CC is an OER catalyst candidate for practical application.

2-Methylbenzimidazole-copper nanozyme with high laccase activity for colorimetric differentiation and detection of aminophenol isomers

Laccase is well-known for its eco-friendly applications in environmental remediation and biotechnology, but its high cost and low stability have limited its practical use. Therefore, there is an urgent need to develop efficient laccase mimetics. In this study, a novel laccase-mimicking nanozyme (MBI-Cu) was successfully synthesized using 2-methylbenzimidazole (MBI) coordinated with Cu2+ by mimicking the copper active site and electron transfer pathway of natural laccase. MBI-Cu nanozyme exhibited excellent catalytic activity and higher stability than laccase, and was utilized to oxidize a series of phenolic compounds. Environmental pollutant aminophenol isomers were found to display different color in solution when catalytically oxidized by MBI-Cu, which provided a simple and feasible method to identify them by the naked eye. Based on the distinct absorption spectra of the oxidized aminophenol isomers, a colorimetric method for quantitatively detecting o-AP, m-AP, and p-AP was established, with detection limits of 0.06 μM, 0.27 μM, and 0.18 μM, respectively. Furthermore, by integrating MBI-Cu-based cotton pad colorimetric strips with smartphone and utilizing color recognition software to identify and analyze the RGB values of the images, a portable colorimetric sensing platform was designed for rapid detection of aminophenol isomers without the need for any analytical instrument. This work provides an effective reference for the design of laccase nanozymes and holds significant potential for applications in the field of environmental pollutant monitoring.

Electronic properties modulation for two-dimensional materials of boron phosphorus monolayer and derived single atom catalysts for the hydrogen evolution reaction

Electrocatalytic hydrogen evolution reaction (HER) is the core of the future renewable energy field and an important part of clean energy technology. It is urgent to find a noble metal free catalyst with high stability, good conductivity and economic efficiency for HER. Two-dimensional (2D) materials such as hexagonal boron nitride formed by the combination of B and N atoms of group III-V elements have been substantiated with significant electronic properties. We predict that 2D materials composed of B and P atoms of the same main group also have good electronic properties. This paper reports for the first time the application of two recent 2D boron phosphorus monolayer compounds (BS-B1P1 and PH-B1P1) as excellent single-atom catalysts (SACs) for HER. We have demonstrated that boron phosphorus compounds can obviously improve its electrical conductivity through single-atom transition metal (TM) doping through the density of state (DOS) calculations, which promises their applications in HER. Hence, an electrocatalyst is computer-aided designed with isolated TM single atom of 3d, 4d, and 5d supported on BS-B1P1 and PH-B1P1 to construct SACs with excellent HER performance. Interestingly, we find that the these SACs can show high HER activity in a wide pH-range. Among all SACs studied, Sc-, Ti-, Nb-, Ag-,and Hf-embedded BS-B1P1 have excellent catalytic activity in acidic conditions while Mn-, Ta-, Re-, Os-, Ir-, and Au-embedded BS-B1P1 show high catalytic activity in alkaline conditions. Mn@PH-B1P1 shows high catalytic activity only in acidic conditions. Especially, Tc@BS-B1P1 system exhibits promising catalytic activity, which owns high active in either neutral, acidic and alkaline conditions. Our work provides a highly active HER catalyst with pH regulation, providing a cost-effective alternative to traditional Pt-based catalysts for sustainable hydrogen extraction.