Enhanced photo-electrocatalytic performance of Pt/RGO/TiO2 on carbon fiber towards methanol oxidation in alkaline media

Insights into the roles of nitrogen and phosphorus co-doping for efficient methanol electrooxidation

Anchoring Pt onto multi-heteroatom doped carbon materials has been recognized as an effective approach to improve the performance of electrocatalytic methanol oxidation. However, distinct contributions and specific behavior mechanisms of different heteroatoms, notably N and P, the specific behavior mechanisms in synergistically promoting Pt NPs remain elusive. In this work, we construct 1D N and P co-doped carbon nanotube (N, P-CNTs) supports with abundant defect anchors for Pt. The as-prepared Pt/N, P-CNTs exhibit outstanding activity and exceptional stability in methanol oxidation reaction (MOR), achieving high mass activity up to 6481.3 mA mg-1Pt. Moreover, they can retain 90.5 % of their initial current density even after 800 cycles tests. Detailed characterizations and theoretical calculations indicate that the robust strong metal-support interactions (SMSI) effect caused by N doping within the unique N and P co-doped coordination structure controllably regulate the coordination environment of Pt, reduce the d-band center of Pt, thus promoting the adsorption and decomposition of CH3OH. However, P doping weakens the adsorption strength of CO on the Pt active site by sacrificing partial electron transfer, accelerating the oxidative conversion of the CO-like poisoning species (COads). Significantly, the synergistic mechanism of N and P species on the modification of Pt's electronic structure and its subsequent impact on the electrocatalytic methanol oxidation behaviors on the Pt surface was thoroughly elucidated, providing a constructive route for designing robust MOR electrocatalysts with high MOR activity and durability.

One-Pot Synthesis of Ultra-Small Pt Dispersed on Hierarchical Zeolite Nanosheet Surfaces for Mild Hydrodeoxygenation of 4-Propylphenol

The rational design of ultra-small metal clusters dispersed on a solid is of crucial importance in modern nanotechnology and catalysis. In this contribution, the concept of catalyst fabrication with a very ultra-small size of platinum nanoparticles supported on a hierarchical zeolite surface via a one-pot hydrothermal system was demonstrated. Combining the zeolite gel with ethylenediaminetetraacetic acid (EDTA) as a ligand precursor during the crystallization process, it allows significant improvement of the metal dispersion on a zeolite support. To illustrate the beneficial effect of ultra-small metal nanoparticles on a hierarchical zeolite surface as a bifunctional catalyst, a very high catalytic performance of almost 100% of cycloalkane product yield can be achieved in the consecutive mild hydrodeoxygenation of 4-propylphenol, which is a lignin-derived model molecule. This instance opens up perspectives to improve the efficiency of a catalyst for the sustainable conversion of biomass-derived compounds to fuels.

Comparison of electrocatalytic activity of Pt1-x Pd x /C catalysts for ethanol electro-oxidation in acidic and alkaline media

In this paper, a comparision of Pt1-x Pd x /C catalysts for ethanol-oxidation in acidic and alkaline media has been investigated. We prepared Pt1-x Pd x /C catalysts with different ratios of Pt/Pd (x at% = 0, 27, 53, 77 and 100) by the formic acid reduction method. The obtained Pt1-x Pd x /C catalysts were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), induced coupled plasma-atomic emission spectroscopy (ICP-AES), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Structural and morphological investigations of the as-prepared catalysts revealed that the metallic particle size increases with increasing Pd content in the catalyst. The electrocatalytic performances and stabilities of Pt1-x Pd x /C catalysts were tested by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and chronoamperometry (CA) measurements for ethanol oxidation in acidic and alkaline media. The electrochemical measurements demonstrate that Pt1-x Pd x /C catalysts exhibit much higher electrocatalytic activity for alcohol oxidation in alkaline media than that in acidic media. The composition of Pt/Pd has a significant impact on the ethanol-oxidation in both acidic and alkaline media. The Pt23Pd77/C catalyst shows the highest electrocatalytic performance with a mass specific peak current of 2453.7 mA mgPtPd -1 in alkaline media, which is higher than the Pt77Pd23/C with the maximum of peak current of 339.7 mA mgPtPd -1 in acidic media. Meanwhile, the effect of electrolyte, CH3CH2OH concentrations and scan rates was also studied for ethanol-oxidation in acidic and alkaline media.

Sensitive measurement of tumor markers somatostatin receptors using an octreotide-directed Pt nano-flakes driven electrochemical sensor

Tumor markers play an important role in the early diagnosis and therapeutic effect monitoring of tumors. An electrochemical biosensor was developed based on multi-branched gold nanoshells (BGSs) and octreotide (OCT) functionalized Pt nano-flakes (PtNFs) modified electrodes, which was used for detection of tumor-specific markers to evaluate tumor cells. Sandwich-type nano-hybrid materials were prepared by layer-by-layer modification. First, reduced graphene oxide (RGO) and BGSs were modified as electronic materials onto glassy carbon electrodes (GCE). This modified electrode has strong electron transfer capability and large electrode surface area. The OCT was then anchored to the surface of BGSs to sensitively detect Somatostatin receptors (SSTRs) on the surface of HeLa cells. In addition, PtNFs were synthesized using a dual-template method, and OCT template on the surface of PtNFs, as an adsorption bioprobe, was used to reduce the H₂O₂ and amplify the electrochemical signal of biosensor. The proposed biosensor can be applied to the quantitative broad linear range of HeLa cells covering from 10 to 1 × 10⁶ cells mL^-1 (R² = 0.9998) and the limit of detection (LOD) was 2 cells mL^-1. The experimental results also show that the sensor has good stability, biocompatibility and high selectivity, which has great potential for clinical application.

Enhanced Photoinduced Electrocatalytic Oxidation of Methanol Using Pt Nanoparticle-Decorated TiO2-Polyaniline Ternary Nanofibers

Herein, perylene-3,4,9,10-tetracarboxylic acid-doped polyaniline (PTP) nanofibers with/without photoreactive anatase TiO₂ (TiO₂-PTP and PTP, respectively) have been successively synthesized and subsequently decorated by Pt nanoparticles (Pt NPs) to prepare Pt-PTP and Pt-TiO₂-PTP composites. High-resolution transmission electron microscopy confirms the presence of ∼3 nm spherical-shaped Pt NPs on both the composites along with TiO₂ on Pt-TiO₂-PTP. Pt loading on the composites is deliberately kept similar to compare the methanol electro-oxidation in the two composites. The Pt nanocomposites along with the precursor polyanilines are characterized by optical characterization, X-ray diffraction study, X-ray fluorescence spectroscopy, and Raman spectroscopy. The ternary composite-modified (Pt-TiO₂-PTP) electrode demonstrates high electrocatalytic performance for methanol oxidation reaction in acid medium than Pt-PTP and Pt-TiO₂. The higher electrochemical surface area (1.7 times), high forward/backward current ratio, and the higher CO tolerance ability for Pt-TiO₂-PTP make it a superior catalyst for methanol oxidation reaction in the electrochemical process than Pt-PTP. Moreover, the catalytic activity of Pt-TiO₂-PTP is further enhanced significantly with light irradiation. The cooperative effects of photo- and electrocatalysis on methanol oxidation reaction in Pt-TiO₂-PTP enhance the methanol oxidation catalytic activity approximately 1.3 times higher in light illumination than in dark. Therefore, the present work will be proficient to get a light-assisted sustainable approach for developing the methanol oxidation reaction activity of Pt NP-containing catalysts in direct methanol fuel cells.

Simple synthesized Pt/GNs/TiO2 with good mass activity and stability for methanol oxidation

Pt/GNs/TiO₂ (GNs, graphene nanosheets) catalyst was synthesized by a simple two-step method, including a rapid solution plasma technique to obtained Pt nanoparticles with a size of 2-5 nm and followed by an ultrasonic mixing of the Pt, GNs and TiO₂ nanoparticles. After coupling with TiO₂ nanoparticles, the Pt/GNs/TiO₂ catalyst exhibited a promoting catalytic activity towards methanol oxidation, which was superior to the Pt/GNs catalyst. The mass activity of the Pt/GNs/TiO₂ catalyst was 3464 mA mg_Pt^-1, which was 3.5 and 3.4 times higher than those of the Pt/GNs and the commercial Pt/C, respectively. And the Pt/GNs/TiO₂ showed a strongly negative shift onset potential of methanol oxidation. The results of long-term cyclic voltammetry and CO-stripping tests showed an improved CO tolerance of the Pt/GNs/TiO₂. Moreover, the mass activity of the Pt/GNs/TiO₂ was further enhanced under light irradiation, with the mass activity of 4715 mA mg_Pt^-1, which was 1.4 times higher than that of in dark. This work provides new opportunities for exploiting efficient visible photo-assisted electro-catalytic methanol oxidation.

Construction of Er3+ :YAlO3 /RGO/TiO2 Hybrid Electrode with Enhanced Photoelectrocatalytic Performance in Methylene Blue Degradation Under Visible Light

Much attention has been paid on doping TiO₂ to narrow its band gap to promote the absorption of visible light and restrain the recombination of electron-hole pairs to improve its efficiency in photoelectrocatalysis (PEC) under visible-light irradiation. However, the oxidation potential energy of photo-induced holes for the modified catalysts by visible-light excitation is lower than that without modification by UV excitation. In this work, we synthesized a co-coupled TiO₂ electrode (denoted ERT) with the Er³⁺ :YAlO₃ and reduced graphene oxide (RGO), achieving the synergetic effect of visible-light-to-UV up-conversion and response and great electron transfer ability. The effects of external bias voltage, electrolyte concentration and pH on the PEC activity were studied with the methylene blue (MB) as the target pollutant. The results indicated that PEC by the ERT electrode showed the highest MB removal compared with those by the electrodes coupled with RGO or Er³⁺ :YAlO₃ alone. In addition, the kinetic rate constant of the PEC process using the ERT electrode was higher than the sum of those of the photocatalytic and electrocatalytic processes. The optimal conditions for PEC by the ERT electrode were an external bias voltage of 1.0 V, 0.1 mol L^-1 Na₂ SO₄ and pH = 10.

Facile synthesis of Pt nanoparticles supported on anatase TiO2 nanotubes with good photo-electrocatalysis performance for methanol

A Pt/TNTs/C catalyst showed enhanced MOR performance under the light illumination.

Nanospherical like reduced graphene oxide decorated TiO2 nanoparticles: an advanced catalyst for the hydrogen evolution reaction

Modification of titanium dioxide (TiO2) for H2 generation is a grand challenge due to its high chemical inertness, large bandgap, narrow light-response range and rapid recombination of electrons and holes. Herein, we report a simple process to prepare nanospherical like reduced graphene oxide (NS-rGO) decorated TiO2 nanoparticles (NS-rGO/TiO2) as photocatalysts. This modified TiO2 sample exhibits remarkably significant improvement on visible light absorption, narrow band gap and efficient charge collection and separation. The photocatalytic H2 production rate of NS-rGO/TiO2 is high as 13996 μmol g(-1) h(-1), which exceeds that obtained on TiO2 alone and TiO2 with parallel graphene sheets by 3.45 and 3.05 times, respectively. This improvement is due to the presence of NS-rGO as an electron collector and transporter. The geometry of NS-rGO should be effective in the design of a graphene/TiO2 composite for photocatalytic applications.

Immobilized Pd(0) nanoparticles on phosphine-functionalized graphene as a highly active catalyst for Heck, Suzuki and N-arylation reactions

Phosphine functionalized graphene was used for the immobilization of Pd nanoparticles and utilized in C–C and C–N bond formation reactions.

Visible light assisted electro–photo synergistic catalysis of heterostructured Pd–Ag NPs/graphene for methanol oxidation

Heterostructured Pd-Ag/GNs catalytic performances for MOR are significantly improved by visible light irradiation: (a) without irradiation, (b) under irradiation.

Oxygen adsorption-induced surface segregation of titanium oxide by activation in carbon nanofibers for maximizing photocatalytic performance

This research demonstrates a simple method for synthesizing titanium dioxide nanoparticle-decorated carbon nanofibers.

Fabrication of SiO2 incorporated ordered mesoporous TiO2 composite films as functional Pt supports for photo-electrocatalytic methanol oxidation

SiO₂ incorporated ordered mesoporous TiO₂ composite films were fabricated as an active support for methanol oxidation and excellent photoelectrocatalytic activity was obtained, showing great potential application prospects.

A facile fabrication of copper particle-decorated novel graphene flower composites for enhanced detecting of nitrite

A novel 3D porous flower-like reduced graphene oxide (f-RGO) was explored as the support material for the Cu particles on glassy carbon electrode (Cu/f-RGO/GCE) for detecting nitrite.

Visible-light-assisted electrocatalytic oxidation of methanol using reduced graphene oxide modified Pt nanoflowers-TiO2 nanotube arrays

In this work, Pt nanoflowers deposited on highly ordered TiO2 nanotube arrays (TNTs) by modification of reduced graphene oxide (RGO) nanostructures have been synthesized. The ternary complex (Pt-TNTs/RGO) displays efficient electrocatalytic performance toward methanol oxidation in alkaline medium. The electrochemical impedance spectroscopy (EIS) and responsive photocurrent results indicate that the presence of graphene could effectively promote charge separation during electrocatalytic process. Interestingly, with assistance of visible light illumination, the electrocatalytic activity and stability of the ternary complex electrode toward methanol oxidation are distinctly improved. Both electro- and photo-catalytic processes for methanol oxidation contribute to the enhanced catalytic performance and stability. Moreover, the ternary electrode also displays efficient photoelectrocatalytic degradation of methylene blue (MB) under visible light illumination. The present work sheds light on developing highly efficient and long-term stability catalysts for methanol oxidation with assistance of visible-light illumination.

Au–Cu–Pt ternary catalyst fabricated by electrodeposition and galvanic replacement with superior methanol electrooxidation activity

The as-fabricated Au–Cu–Pt/GCE ternary catalyst exhibits flower-like cluster morphology and superior catalytic activity toward methanol electrooxidation.