Tailoring Charge Flow in Carbon-Defective Cu-MOF with Pd Nanoparticles: A Boost for Visible Light Organic Photoelectrochemical Transistor in Bioanalysis.

The photoactive material was of significant importance in organic photoelectrochemical transistor (OPECT) bioanalysis as it influences the photoinduced voltage and the µC* product, resulting in a varying sensor sensitivity. The utilization of metal-organic frameworks (MOFs) as photoactive materials in OPECT analysis is promising, yet it remains a grand challenge due to the inherently narrow light absorption range and high electron-hole recombination rate. Herein, Pd NPs were encapsulated as electron acceptors into the Cu-MOF using a double-solvent method, followed by pyrolysis at the proper temperature. After pyrolysis, Cu-MOF transformed into a carbon defect-rich composite of CuO and Cu2O while retaining its high porosity and structural morphology. The resulting carbon defect-rich pyrolysis Cu-MOF (p-Cu-MOF) served as an active support, facilitating the separation of electrons and holes. The photoelectrons trigger the electron transfer of adjacent active metal components and the formation of a Schottky junction between Pd and the MOFs. This effect induces the electron donation from the MOFs. Moreover, Pd/pyrolysis Cu-MOF exhibits significantly higher visible light absorption, better water stability, and higher electrical conductivity compared to Cu-MOF and Pd/Cu-MOF. An OPECT sensor was fabricated by utilizing Pd/p-Cu-MOF as the photoactive material and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as the channel material on an integrated laser-etched FTO. The aptamer was used as the recognition element, enabling sensitive and efficient detection of residual isocarbophos.

A 2D Nano-architecture (NPSMC@Ir-Ru@rGO) Derived from Graphene Enfolded Polyphosphazene Nanospheres Decorated Ir-Ru Metals (PZS@Ir-Ru@GO) towards Bifunctional Water Splitting.

A leap-forward approach has been successfully devised to synthesize a novel hierarchical binary metal modified heteroatom doped 2D micro-/mesporous carbon-graphene nanostructure (NPSMC@Ir-Ru@rGO) for overall water splitting application. To investigate the role of decorating metals, different electrolcatalysts like NPSMC, NPSMC@rGO, NPSMC@Ir@rGO, and NPSMC@Ru@rGO were also synthesized and structural changes were compared and investigated by physiochemical techniques. All of the samples have shown electrocatalytic activities attributed to the presence of heteroatom (N, P, S) doped micro-/mesoporous carbonaceous matrix, amorphous carbon in the coexistence of graphitic lattice carbons, presence of active metal NPs (Ir and/-or Ru), an even distribution of active sites, and graphene 2D interconnected channels to promote electron transfer ability, respectively. However, the Ir-Ru metal codeped nanocatalyst (NPCMS@Ir-Ru@rGO) is proved to be an excellent electrocatalyst based on the synergistic role of Ir-Ru metals that necessitates the low overpotentials of 181 mV and 318 mV to convey a current density of 10 mA cm-2 towards the electroctalytic application of HER and OER, respectively. Furthermore, exhibiting the corresponding Tafel slopes (132 and 70 mV dec-1 ) in an alkaline medium. This work is anticipated to open up new avenues for the development of promising electrocatalysts based on active metals modified heteroatom doped carbon nanomaterials for energy applications.

A Single Step Fast Track Methodology for In-Situ Detection of Hazardous Melamine by Using Highly Sensitive Polyphenolics Modified Nanogold Probe.

A single step fast track method is proposed to determine melamine based on strong hydrogen bonding between exocyclic amine group in melamine moiety and hydroxyl group of tannic acid (TA); acting as reducing and functionalizing agent for synthesis of gold nanoparticles (Au NPs). The proposed strategy is facile and highly time saving; as the detection of melamine with labelfree gold nanoparticles was accomplished within five minutes. The colorimetric probe exhibits high detection limit of 8 nM for melamine determination in raw milk, which is very low as compared to other capping ligands employed for Au NPs such as borohydride, citrate and 3,5-dihydroxybenzoic acid. The results show a highly sensitive linear range (0.03-2.5 µM) between absorption ratio and concentration of melamine with a correlation coefficient of 0.991. Proposed methodology is proven effective for on-site screening without using costly instrumentation.

Colorimetric paper sensor for sensitive detection of explosive nitroaromatics based on Au@Ag nanoparticles.

Rapid, reliable, onsite approaches for detection trace level of trinitrotoluene (TNT) is a pressing necessity for both homeland security and environmental protection. To this end, hydrophilic amine(-NH2) protected Au@Ag nanoparticles (NPs) were developed and fabricated as colorimetric paper sensor for delicate detection of TNT. The as-developed nanoprobe selectively reacts with TNT through classic Meisenheimer complex formation by means of charge transfer process from an electron-rich NH2 group of ß-cysteamine to an electron-deficient nitro group on TNT. Due to the absence of this particular interaction of other nitroaromatics, the proposed probe is highly selective for TNT detection with a better linear range (0-20 µg/mL) and limit of detection (LOD) of 0.35 µg/mL. The present work provides a novel and facile strategy to fabricate colorimetric paper sensors with rapid and selective recognition ability for label free analysis of TNT.

A pH-responsive nanoprobe for turn-on 19F-magnetic resonance imaging.

We successfully fabricated 19F magnetic resonance imaging (MRI) nanoprobes by partly replacing the 2-methylimidazolate of the metal organic framework (MOF) matrix ZIF-8, of which the strong 19F MRI signal displays an interesting pH dependence property, indicating its great potential as a 19F MRI contrast agent for stimuli-responsive imaging with high penetration depth and low background.

From a ureidopyrimidinone containing organic precursor to excavated iron-nitrogen codoped hierarchical mesoporous carbon (Ex-FeN-MC) as an efficient bifunctional electrocatalyst.

A hierarchical excavated iron-nitrogen codoped mesoporous carbon (Ex-FeN-MC) electrocatalyst has been successfully synthesized by pyrolysis of the unique ureidopyrimidinone containing organic precursor MAMIS by using silica as the mesoporous template and iron nitrate as the source of iron. The selected organic precursor has multifunctionalities with diverse distribution of nitrogen and oxygen species which constitute interesting features to prepare the Ex-FeN-MC electrocatalyst. The as-prepared Ex-FeN-MC material shows unexpectedly higher catalytic activities towards ORR/OER performances with an overpotential of 250 mV for OER in alkaline solution at a current density of 10 mA cm-2, while the ORR activity is almost similar to that of commercial Pt/C. It is believed that the excellent electrochemical performance results from the synergic contribution of the hierarchical uniform mesoporous structure, evenly distributed iron nanoparticles and high density of Ex-FeN-MC catalytically active sites. The presence of the hierarchical uniform mesoporous structure considerably accelerates the mass transfer and efficiently promotes the full utilization of active sites. Furthermore, it also possesses amorphous carbon in coexistence with lattice graphitic carbon which also enhanced the ORR/OER performances. Our research findings can surely provide a new insight to design highly active ORR/OER electrocatalysts by utilizing more novel organic precursors to provide interesting characteristics to electrocatalysts, as well as open up a route for constructing unique multifunctional materials with mesoporous architectures for electrocatalysis and supercapacitor applications.