Ambient hydrogenation of solid aromatics enabled by a high entropy alloy nanocatalyst.

Hydrogenation is a versatile chemical process with significant applications in various industries, including food production, petrochemical refining, pharmaceuticals, and hydrogen carriers/safety. Traditional hydrogenation of aromatics, hindered by the stable π-conjugated phenyl ring structures, typically requires high temperatures and pressures, making ambient hydrogenation a grand challenge. Herein, we introduce a PdPtRuCuNi high entropy alloy (HEA) nanocatalyst, achieving an exceptional 100% hydrogenation of carbon-carbon unsaturated bonds, including alkynyl and phenyl groups, in solid 1,4-bis(phenylethynyl)benzene (DEB) at 25 °C under ≤1 bar H2 and solventless condition. This results in a threefold higher hydrogen uptake for DEB-contained composites compared to conventional Pd catalysts, which can only hydrogenate the alkynyl groups with a ~ 27% conversion of DEB. Our experimental results, complemented by theoretical calculations, reveal that PdPtRu alloy is highly active and crucial in enabling the hydrogenation of phenyl groups, while all five elements work synergistically to regulate the reaction rate. Remarkably, this newly developed catalyst also achieves nearly 100% reactivity for ambient hydrogenation of a broad range of aromatics, suggesting its universal effectiveness. Our research uncovers a novel material platform and catalyst design principle for efficient and general hydrogenation. The multi-element synergy in HEA also promises unique catalytic behaviors beyond hydrogenation applications.

Insights into the enhanced hydrogen adsorption on M/La2O3 (M = Ni, Co, Fe).

Lanthanum oxide (La2O3) possesses superior reactivity during catalytic hydrogenation, but the intrinsic activity of La2O3 toward H2 adsorption and activation remains unclear. In the present work, we fundamentally investigated hydrogen interaction with Ni-modified La2O3. Hydrogen temperature programmed desorption (H2-TPD) on Ni/La2O3 shows enhanced hydrogen adsorption with a new hydrogen desorption peak at a higher temperature position compared to that on the metallic Ni surfaces. By systematically exploring the desorption experiments, the enhanced H2 adsorption on Ni/La2O3 is due to the oxygen vacancies formed at the metal-oxide interfaces. Hydrogen atoms transfer from Ni surfaces to the oxygen vacancies to form lanthanum oxyhydride species (H-La-O) at the metal-oxide interfaces. The adsorbed hydrogen at the metal-oxide interfaces of Ni/La2O3 results in improved catalytic reactivity in CO2 methanation. Furthermore, the enhanced hydrogen adsorption on the interfacial oxygen vacancies is ubiquitous for La2O3-supported Fe, Co, and Ni nanoparticles. Benefiting from the modification effect of the supported transition metal nanoparticles, the surface oxyhydride species can be formed on La2O3 surfaces, which resembles the recently reported oxyhydride observed on the reducible CeO2 surfaces with abundant surface oxygen vacancies. These findings strengthen our understanding of the surface chemistry of La2O3 and shed new light on the design of highly efficient La2O3-based catalysts with metal-oxide interfaces.

Reusable OIRD Microarray Chips Based on a Bienzyme-Immobilized Polyaniline Nanowire Forest for Multiplexed Detection of Biological Small Molecules.

Quantitative detection of multiple biological small molecules is critical for health evaluation and disease diagnosis. In this study, a microarray chip featuring a bienzyme-immobilized polyaniline nanowire forest on fluorine-doped tin oxide (bienzyme-PANI/FTO) is developed for this purpose. On such a chip, the target molecules are oxidized under the catalysis of their attached oxidases to produce hydrogen peroxide, which further induces the partial oxidation of local PANI nanowires in the presence of horseradish peroxidase (HRP) enzyme. The redox state change of PANI nanowires is monitored by the oblique incident reflectivity difference (OIRD) technique in a real-time and wireless manner, thus allowing for quantitative analysis of the target molecules. As typical model targets, hydrogen peroxide, glucose, lactic acid, and cholesterol are successfully detected with low detection limits, excellent specificities, and broad detection ranges, all of which fully meet the requirements for clinical analysis of human serum samples. Simultaneous detection of multiple targets on an individual chip is further demonstrated using the OIRD scanning mode. Meanwhile, by simple electrochemical reduction of the PANI nanowires, the chip is reusable for more than eight detection cycles without evident decay in its performance. The detection principle of this chip is also universal to other small molecules, and thus, it shows great promise as a valuable device to analyze biological small molecules.

A microwell array structured surface plasmon resonance imaging gold chip for high-performance label-free immunoassay.

Surface plasmon resonance imaging (SPRi) offers a compelling method for high-throughput, real-time, and label-free biomolecular interaction studies and immunoassays, but its performance suffers from limited intrinsic sensitivity and low-contrast SPRi images. Herein we report a high-performance SPRi chip featuring patterned microwell array constructed by photolithography of adhesive polydopamine (PDA) thin film on conventional gold chip. The chip allows for the facile construction of region-defined sensing array on its surface with improved intrinsic SPRi sensitivity due to the intensified surface plasmon wave (SPW) in the microwells. The immunoassay performance of the as-designed SPRi chip is evaluated by using anti-ochratoxin A (anti-OTA) monoclonal antibody as a model target. The results show that this microwell array structured gold chip exhibits ca. 18%-32% higher signal intensity than the conventional gold chip when detecting anti-OTA at different concentrations, and the noise remains at the same level, showing enhanced intrinsic sensitivity. Meanwhile, this microwell-structured chip affords clear and high-contrast SPRi images with well-defined sensing areas, which greatly facilitates the extraction and quantitative analysis of detection signals while efficiently suppressing the disturbance from background areas.

Optical imaging of the potential distribution at transparent electrode/solution interfaces.

Measuring the electrode potential with spatio-temporal resolution is of essential importance for surface electrochemistry, energy storage and conversion among others. Optical imaging of the electrode potential distribution on transparent electrodes (ITO, FTO and single-layer graphene, etc.) is successfully achieved by using oblique incident reflectivity difference (OIRD) technology.

Spatially resolved electrochemical reversibility of a conducting polymer thin film imaged by oblique-incidence reflectivity difference.

The spatially resolved electrochemical reversibility of a polyaniline (PANI) thin film is successfully imaged by an oblique-incidence reflectivity difference (OIRD) technique. The electrochemical conversion of the PANI thin film from its completely reduced state to partially oxidized state gives rise to a considerable OIRD signal while upon the deterioration of the electrochemical reversibility, this OIRD signal decreases.

Benchmarking Three Ruthenium Phosphide Phases for Electrocatalysis of the Hydrogen Evolution Reaction: Experimental and Theoretical Insights.

The outstanding electrocatalytic activity of ruthenium (Ru) phosphides toward the hydrogen evolution reaction (HER) has received wide attention. However, the effect of the Ru phosphide phase on the HER performance remains unclear. Herein, a two-step method was developed to synthesize nanoparticles of three types of Ru phosphides, namely, Ru2 P, RuP, and RuP2 , with similar morphology, dimensions, loading density, and electrochemical surface area on graphene nanosheets by simply controlling the dosage of phytic acid as P source. Electrochemical tests revealed that Ru2 P/graphene shows the highest intrinsic HER activity, followed by RuP/graphene and RuP2 /graphene. Ru2 P/graphene affords a current density of 10 mA cm-2 at an overpotential of 18 mV in acid media. Theoretical calculations further showed that P-deficient Ru2 P has a lower free energy of hydrogen adsorption on the surface than other two, P-rich Ru phosphides (RuP, RuP2 ), which confirms the excellent intrinsic HER activity of Ru2 P and is consistent with experiment results. The work reveals for the first time a clear trend of HER activity among three Ru phosphide phases.

Single-layer graphene-coated gold chip for electrochemical surface plasmon resonance study.

Surface plasmon resonance (SPR) employs a gold (Au) thin film (ca. 50 nm in thickness) chip to generate a surface plasmonic wave (SPW) for in situ monitoring of the interface/surface, which makes it intrinsically compatible with electrochemistry for combined electrochemical surface plasmon resonance (EC-SPR) investigations. However, conventional SPR Au chips suffers from a high background signal, narrow electrochemical window, and limited electrochemical stability. Presented in this work is a novel SPR chip composed of the Au/long-chain alkane thiol self-assembled monolayer/single-layer graphene (Au/SAM/G) sandwich architecture to address these problems. On this chip, the single-layer graphene serves as a working electrode for electrochemical measurement, and the underlying Au film serves as the SPW support for SPR monitoring; the sandwiched thiol monolayer enables the electrical separation of the graphene and Au film to protect the Au film from electrochemical polarization. Our experiment indicates that the electrochemical window of such a chip extends beyond the hydrogen/oxygen evolution reaction potential on Au with significantly improved electrochemical stability and suppressed background signal. Moreover, its intrinsic SPR sensitivity is completely reserved even compared to that of the conventional SPR Au chip. This Au/SAM/G chip may offer a valuable solution to the EC-SPR investigations in harsh conditions. Graphical abstract ᅟ.

Mesoporous Hollow Nitrogen-Doped Carbon Nanospheres with Embedded MnFe2O4/Fe Hybrid Nanoparticles as Efficient Bifunctional Oxygen Electrocatalysts in Alkaline Media.

Exploring sustainable and efficient electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is necessary for the development of fuel cells and metal-air batteries. Herein, we report a bimetal Fe/Mn-N-C material composed of spinel MnFe2O4/metallic Fe hybrid nanoparticles encapsulated in N-doped mesoporous hollow carbon nanospheres as an excellent bifunctional ORR/OER electrocatalyst in alkaline electrolyte. The Fe/Mn-N-C catalyst is synthesized via pyrolysis of bimetal ion-incorporated polydopamine nanospheres and shows impressive ORR electrocatalytic activity superior to Pt/C and good OER activity close to RuO2 catalyst in alkaline environment. When tested in Zn-air battery, the Fe/Mn-N-C catalyst demonstrates excellent ultimate performance including power density, durability, and cycling. This work reports the bimetal Fe/Mn-N-C as a highly efficient bifunctional electrocatalyst and may afford useful insights into the design of sustainable transition-metal-based high-performance electrocatalysts.