Screening of transition metal and boron atoms co-doped graphdiyne catalysts for electrocatalytic urea synthesis

Designing an optical sensor with exceptional sensitivity and specificity for the detection of ultra-trace amounts of boron

A specialized optical chemical sensor for boron detection was designed using a polymer inclusion membrane (PIM). This unique sensor relies on an encapsulation method to create its optical membrane. The components involved in this sensor include azomethine H (AMH) as the reactive agent, polyvinyl chloride as the foundational polymer, and dinonylnaphthalene sulphonic acid (DNNS) as the extraction agent within the PIM structure. Various parameters, such as membrane thickness, concentration of AMH and DNNS, plasticizer proportions, stirring dynamics, and the pH of the solution under study, significantly affected the sensor's performance. Within a detection range spanning 4.0-116 ng mL-1 of boron, the sensor demonstrated a strong linear relationship with detection and quantification thresholds of 1.25 and 3.94 ng mL-1, respectively. The peak absorption wavelength (λmax) for this PIM-based sensor was identified at 424 nm. Moreover, the sensor displayed a reproducibility (RSD) of 1.65% and a repeatability RSD of 1.43%, coupled with a swift response time of approximately 3.0 min. The membrane selectivity was tested against boron in acidic environments. This proposed sensor effectively detected boron in diverse samples such as water, vegetation, soil, and ceramic samples, with findings corroborated by an AAS technique.

Interfacial Electronic Interactions Between Ultrathin NiFe-MOF Nanosheets and Ir Nanoparticles Heterojunctions Leading to Efficient Overall Water Splitting

Creating specific noble metal/metal-organic framework (MOF) heterojunction nanostructures represents an effective strategy to promote water electrolysis but remains rather challenging. Herein, a heterojunction electrocatalyst is developed by growing Ir nanoparticles on ultrathin NiFe-MOF nanosheets supported by nickel foam (NF) via a readily accessible solvothermal approach and subsequent redox strategy. Because of the electronic interactions between Ir nanoparticles and NiFe-MOF nanosheets, the optimized Ir@NiFe-MOF/NF catalyst exhibits exceptional bifunctional performance for the hydrogen evolution reaction (HER) (η10 = 15 mV, η denotes the overpotential) and oxygen evolution reaction (OER) (η10 = 213 mV) in 1.0 m KOH solution, superior to commercial and recently reported electrocatalysts. Density functional theory calculations are used to further investigate the electronic interactions between Ir nanoparticles and NiFe-MOF nanosheets, shedding light on the mechanisms behind the enhanced HER and OER performance. This work details a promising approach for the design and development of efficient electrocatalysts for overall water splitting.

Theoretical study of transition metal-doped β12 borophene as a new single-atom catalyst for carbon dioxide electroreduction

The electrocatalytic carbon dioxide reduction reaction (CO2RR) presents a viable and cost-effective approach for the elimination of CO2 by transforming it into valuable products. Nevertheless, this process is impeded by the absence of exceptionally active and stable catalysts. Herein, a new type of electrocatalyst of transition metal (TM)-doped β12-borophene (TM@β12-BM) is investigated via density functional theory (DFT) calculations. Through comprehensive screening, two promising single-atom catalysts (SACs), Sc@β12-BM and Y@β12-BM, are successfully identified, exhibiting high stability, catalytic activity and selectivity for the CO2RR. The C1 products methane (CH4) and methanol (CH3OH) are synthesized with limiting potentials (UL) of -0.78 V and -0.56 V on Sc@β12-BM and Y@β12-BM, respectively. Meanwhile, CO2 is more favourable for reduction into the C2 product ethanol (CH3CH2OH) compared to ethylene (C2H4) via C-C coupling on these two SACs. More importantly, the dynamic barriers of the key C-C coupling step are 0.53 eV and 0.73 eV for the "slow-growth" sampling approach in the explicit water molecule model. Furthermore, Sc@β12-BM and Y@β12-BM exhibit higher selectivity for producing C1 compounds (CH4 and CH3OH) than C2 (CH3CH2OH) in the CO2RR. Compared with Sc@β12-BM, Y@β12-BM demonstrates superior inhibition of the competitive hydrogen evolution reaction (HER) in the liquid phase. These results not only demonstrate the great potential of SACs for direct reduction of CO2 to C1 and C2, but also help in rationally designing high-performance SACs.

Screening of Transition Metal Supported on Black Phosphorus as Electrocatalysts for CO2 Reduction

The electrocatalytic CO2 reduction (CO2RR) is an effective and economical strategy to eliminate CO2 through conversion into value-added chemicals and fuels. However, exploring and screening suitable 2D material-based single-atom catalysts (SACs) for CO2 reduction are still a great challenge. In this study, 27 (3d, 4d, and 5d, except Tc and Hg) transition metal (TM) atom-doped black phosphorus (TM@BP) electrocatalysts were systematically investigated for CO2RR by density functional theory calculations. According to the stability of SACs and their effectiveness in activating the CO2 molecule, three promising catalysts, Zr@BP, Nb@BP, and Ru@BP, were successfully screened out, exhibiting outstanding catalytic activity for the production of carbon monoxide (CO), methyl alcohol (CH3OH), and methane (CH4) with limiting potentials of -0.79, -0.49, and -0.60 V, respectively. A catalytic relationship between the d-band centers of SACs and the limiting potential of CO2RR was used to estimate the catalytic activity of catalysts. Furthermore, Nb@BP has high selectivity for CO2RR to CH3OH compared to H2 formation, while the hydrogen evolution reaction significantly impacts the synthesis of CO and CH4 on Zr@BP and Ru@BP. Nitrogen atom doping in BP is beneficial for enhancing the selectivity of CO2RR, but it is detrimental to the activity of CO2RR. This study offers theoretical guidance for synthesizing highly efficient CO2RR electrocatalysts and further enhances structural modulation methods for layered 2D materials.