Synthesis of Solvent-Mediated Morphology-Controlled PdSn Alloy Nanocatalysts and their Application in Electrocatalysis of Ethylene Glycol and Ethanol.

2D nanodendrites (NDs) and nanosheets (NSs) have been regarded as efficient nanocatalysts for enhancing the electrocatalytic performance due to their low coordinated sites and abundant electrocatalytic centers. Nevertheless, it remains challenging to construct advanced NDs and NSs in a single reaction system. Herein, by tuning the volume ratios of mixed solvents, the reduction and diffusion rate of Sn2+ on Pd NSs template was rationally controlled to prepare PdSn NDs and PdSn NSs. Ascribed to the open 2D nanostructure, high specific surface area, and robust synergistic effect, the as-prepared PdSn NDs and PdSn NSs exhibited distinguished electrocatalytic activities for ethylene glycol oxidation reaction (EGOR) and ethanol oxidation reaction (EOR), as well as commendable electrocatalytic durability, which were far superior to the Pd NSs and commercial Pd/C. In addition, the PdSn NDs exhibited enhanced reaction kinetics because the characteristic branch structure exposed a high density of active sites. This work may provide significant guidance for preparing excellent nanocatalysts with various morphological features by simply optimizing the content of the coexisting solvents.

In Situ Electrodeposition of Ultralow Pt into NiFe-Metal-Organic Framework/Nickel Foam Nanosheet Arrays as a Bifunctional Catalyst for Overall Water Splitting.

Exploring highly effective bifunctional electrocatalysts with surface structural advantages and synergistic optimization effects among multimetals is greatly important for overall water splitting. Herein, we successfully synthesized Pt-loaded NiFe-metal-organic framework nanosheet arrays grown on nickel foam (Pt-NiFe-MOF/NF) via a facile hydrothermal-electrodeposition process. Benefiting from large exposed specific surface, optimal electrical conductivity and efficient metal-support interaction endow Pt-NiFe-MOF/NF with highly catalytic performance, exhibiting small overpotential of 261 mV toward oxygen evolution reaction and 125 mV toward hydrogen evolution reaction at a current density of 100 mA cm-2 in alkaline medium. More significantly, the assembled water electrolyzer comprising the Pt-NiFe-MOF/NF//Pt-NiFe-MOF/NF couple demands a low cell voltage of 1.45 V to reach 10 mA cm-2. This work renders a viable approach to design dual-functional electrocatalysts with exceptional electrocatalytic activity and stability at high current density, showing the great prospect of water electrolysis for commercial application.

Rapid synthesis of Palladium-Platinum-Nickel ultrathin porous nanosheets with high catalytic performance for alcohol electrooxidation.

Bimetallic two-dimensional (2D) nanomaterials are widely used in electrocatalysis owing to their unique physicochemical properties, while trimetallic 2D materials of porous structures with large surface area are rarely reported. In this paper, a one-pot hydrothermal synthesis of ternary ultra-thin PdPtNi nanosheets is developed. By adjusting the volume ratio of the mixed solvents, PdPtNi with porous nanosheets (PNSs) and ultrathin nanosheets (UNSs) was prepared. The growth mechanism of PNSs was investigated through a series of control experiments. Notably, thanks to the high atom utilization efficiency and fast electron transfer, the PdPtNi PNSs have remarkable activity of methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR). The mass activities of the well-tuned PdPtNi PNSs for MOR and EOR were 6.21 A mg-1 and 5.12 A mg-1, respectively, much higher than those of commercial Pt/C and Pd/C. In addition, after durability test, the PdPtNi PNSs exhibited desirable stability with the highest retained current density. Therefore, this work provides a significant guidance for designing and synthesizing a new 2D material with excellent catalytic performance toward direct fuel cells applications.

Photoelectrocatalytic oxidation of ethylene glycol on trimetallic PdAgCu nanospheres enhanced by surface plasmon resonance.

The notable surface plasmon resonance (SPR) effect of some metals has been applied to improve the efficiency of alcohol oxidation reactions, whereas the comprehensive investigation of Cu-assisted photoelectrocatalysis remains challenging. We herein successfully prepared trimetallic PdAgCu nanospheres (NSs) with abundant surface bulges for the advanced ethylene glycol oxidation reaction (EGOR) and compared them with bimetallic PdAg NSs to investigate the performance enhancement mechanism. Impressively, the as-optimized PdAgCu NSs exhibited superb mass activity and electrochemical stability. Moreover, under visible light illumination, the mass activity of PdAgCu NSs increased to 1.62 times compared to that in the dark, and in contrast, the mass activity of PdAg NSs only increased to 1.48 times that in the dark. A mechanistic study indicated that the incorporation of Cu not only strengthens the whole SPR effect of PdAgCu NSs but also further modifies the electronic structure of Pd. This work highlighted that the incorporation of Cu into PdAg NSs further enhanced the photoelectrocatalytic performance and increased noble metal atom utilization, which may provide guidance to fabricate novel and promising nanocatalysts in the field of photoelectrocatalysis.

Ultrasensitive photoelectrochemical immunosensor for carcinoembryonic antigen detection based on pillar[5]arene-functionalized Au nanoparticles and hollow PANI hybrid BiOBr heterojunction.

In this study, an ultrasensitive and specific photoelectrochemical (PEC) immunosensor was designed for carcinoembryonic antigen (CEA) detection. Benefitting from the ascorbic acid (AA) used as an electron donor that led to a notable change in the photocurrent density, pillar[5]arene functionalized Au and Polyaniline-Bismuth oxybromide heterojunction (Au@WP5/PANI-BiOBr) displayed superior PEC performance for CEA sensing. In detail, the localized surface plasmon resonance (LSPR) of the Au NPs and host-guest complexation between WP5 and AA increased the photocurrent signal, the photogenerated holes on BiOBr accelerated the oxidation of AA, and the fast electron transfer of the hollow PANI tubes benefited an increase in the photocurrent. The antibody effectively bound with CEA when bovine serum albumin blocked the residual sites on the Au@WP5/PANI-BiOBr electrode, generating a clear decrease in photocurrent density in AA solution. Under the optimum condition, the developed PEC immunosensor exhibited a sensitive response to CEA which was linear in the range of 0.01 ng mL-1 to 50 ng mL-1 with a detection limit of 3 pg mL-1. The proposed PEC immunosensor displayed high specificity, good stability, and excellent reproducibility, paving a new way to construct sensitive and specific photoactive heterojunction materials for biomarker immunosensing.

Fabrication of cobaltous telluride and carbon composite as a promising carrier for boosting electro oxidation of ethylene glycol on palladium in alkaline medium.

The development of highly active and earth-rich electrocatalysts remains a formidable challenge for the commercialization of fuel cells. Herein, a composite carrier composed of cobaltous telluride (CoTe) and carbon (C) has been designed for the first time to enhance the electrocatalytic performance of palladium (Pd) nanoparticles (NPs) for the electro-oxidation of ethylene glycol (EG). Remarkably, the mass activity for the as-prepared Pd/CoTe-C catalyst during the ethylene glycol oxidation reaction (EGOR) is found to reach up to 3917.3 mA mg-1, which is 2.2 times higher than that of Pd/Co-C (1785.0 mA mg-1) and 4.1 times greater than that of commercial Pd/C catalyst (962.4 mA mg-1), exceeding that obtained for most Pd-based electrocatalysts reported thus far. In particular, the Pd/CoTe-C catalyst shows better electrochemical stability toward the EGOR than the Pd/Co-C and commercial Pd/C catalysts. Thus, the Pd/CoTe-C electrocatalyst is expected to exhibit broad application prospects in the field of fuel cells.

Core@shell PtAuAg@PtAg Hollow Nanodendrites as Effective Electrocatalysts for Methanol and Ethylene Glycol Oxidation.

Pt-based catalysts with core@shell structures are widely used in alcohol oxidations due to their excellent catalytic performance. In this work, we synthesized a series of core@shell PtAuAg@PtAg hollow nanodendrites (HNDs) with different compositions by a simple seed-mediated method. The PtAuAg@PtAg HNDs with a hollow core and dendritic shell exhibit excellent catalytic performance for ethylene glycol oxidation reaction (EGOR) and methanol oxidation reaction (MOR). Among these, Pt38Au29Ag33 HNDs have the highest mass activity (12364.0 mA mgPt-1/3278.0 mA mgPt-1) for EGOR and MOR, which is 4.2 times and 5.3 times higher than that of commercial Pt/C (2941.0 mA mgPt-1/617.6 mA mgPt-1), respectively. More importantly, after successive cyclic voltammetry tests, the retained mass activities of Pt38Au29Ag33 HNDs are 3913.8 mA mgPt-1 and 348.3 mA mgPt-1, which are much higher than that of commercial Pt/C as well. The excellent catalytic performance of PtAuAg@PtAg HNDs can be attributed to the structure of HNDs, which can greatly increase the surface area and active sites, as well as the electronic and synergistic effects among Pt, Au, and Ag. This research may provide new ideas for the development of high-efficiency hollow catalytic materials for EGOR and MOR.

Rod-like MnO2 boost Pd/reduced graphene oxide nanocatalyst for ethylene glycol electrooxidation.

Anode catalyst is one of the core components of fuel cell, but its poor catalytic activity, short lifespan, and high price are tricky problems to the commercialization of fuel cell. Herein, a novel rod-like MnO2 decorated reduced graphene oxide (RGO) supported Pd hybrid (Pd/RGO-MnO2) has been designed, which manifests more negative onset oxidation potential, higher peak current density, and better long-term stability relative to Pd/RGO and pure Pd catalysts when serving for ethylene glycol electrooxidation. This enhancement may be due to the addition of MnO2, which can effectively promote the adsorption of hydroxyl at a lower potential and produce a strong electronic interaction with Pd, as confirmed by X-ray photoelectron spectroscopy (XPS) technique. In view of its excellent performance and low cost, Pd/RGO-MnO2 is considered to be a potential and effective anode catalyst for DEGFCs.

Trimetallic platinum-nickel-palladium nanorods with abundant bumps as robust catalysts for methanol electrooxidation.

The development of high-performance catalysts is of great importance in direct alcohol fuel cells. One dimensional nanorods catalysts are hopeful candidates as efficient alcohol electrocatalysis. However, it is desirable to precisely modulate the surface morphology of one dimensional nanorods nanocrystals to acquire better catalytic property. We effectively integrate properties of robust one dimensional nanorods, core@shell structure, and ternary nanoalloy into a new PtNiPd@Pt core@shell nanorods with high density bumps on the surface for potential better catalytic behaviors. Notably, those unique structures make the PtNiPd@Pt nanocrystals display favorable electrocatalytic performance towards methanol oxidation reaction. Specifically, the composition-optimized PtNi0.20Pd0.52 nanorods exhibit the highest methanol oxidation reaction specific activity of 18.01 mA cm-2 among PtNiPd@Pt catalysts in alkaline condition. The specific activity is 8.5 times higher than that of Pt/C catalysts. Moreover, electrochemical stability measurements also confirm the better reaction endurance of PtNi0.20Pd0.52 nanorods. Our work provides a reference to well tune the fine surface structure on one dimensional nanorods catalysts in the direction of superior electrocatalytic behaviors.

Monodispersed bimetallic platinum-copper alloy nanospheres as efficient catalysts for ethylene glycol electrooxidation.

Designing and fabricating highly active and efficient catalysts are of vital importance for the practical applications of direct ethylene glycol fuel cells (DEGFCs). In this study, we employ a feasible one-pot synthetic method to construct highly monodispersed PtCu nanospheres (NSs) as high-efficiency anode electrocatalysts for DEGFCs. Interestingly, the optimized carbon supported Pt1Cu1 NSs can display the highest mass activity of 2146.9 mA mg-1 in 1 M KOH + 1 M EG solution under the scan rate of 50 mV s-1, which is 1.9 times higher than that of commercial Pt/C catalysts. This is ascribed to the favorable electronic effect between Pt and Cu, which is beneficial for ethylene glycol oxidation reaction (EGOR) in fuel cells. Meanwhile, such monodispersed Pt1Cu1 NSs can also exhibit excellent durability, where the Pt1Cu1 catalyst retains 62.6% of the initial value after the cyclic voltammetry of 500 cycles. This work not only provides a significant approach for designing catalysts for fuel cells, but also constructs a novel class of active and stable electrocatalysts for EGOR.

Anchoring gold nanoparticles on poly(3,4-ethylenedioxythiophene) (PEDOT) nanonet as three-dimensional electrocatalysts toward ethanol and 2-propanol oxidation.

Renewable alcohol oxidation is of vital significance for clean energy conversion and storage. Here, we fabricated a three-dimensional (3D) nanonet-like hybrid catalyst combining Au nanoparticles and poly(3,4-ethylenedioxythiophene) (PEDOT) together, in which PEDOT nanonets act as the framework of the 3D catalyst and the support for the dispersion of Au nanoparticles. The catalyst was designated as Au-PEDOT. By using conductive carbon cloth (CC) as electrode substrates, the as-fabricated Au-PEDOT/CC electrodes were applied to evaluate the electrocatalytic activity towards ethanol and 2-propanol in the alkaline media, respectively. The catalytic activity on Au-PEDOT/CC in terms of the peak current and/or peak current density towards ethanol and 2-propanol oxidation is five times higher than that on comparative Au/CC catalysts, respectively, which is also higher than that on some similar materials reported in the literature. In addition, the Au-PEDOT/CC electrode also possessed great durability and reproducibility. This enhancement in electrocatalytic activity can be attributed to a number of factors: the nano-scale of the Au catalysts, the 3D nanostructure of the catalysts, the conductivity of PEDOT, as well as the effect of alkaline media. These results indicate the as-synthesized Au-PEDOT is a promising electrocatalyst for liquid fuel oxidation.

Uniform PdCu coated Te nanowires as efficient catalysts for electrooxidation of ethylene glycol.

The renewable alcohol oxidation reaction is critical to conversion and storage of clean energy, but the design and construction of highly efficient catalysts for boosting the electrooxidation reaction, remains a grand challenge. Here, we propose a facile approach for the large-scale generation of uniform PdCuTe nanowires (NWs) by using Te NWs as the template. Impressively, as a robust integrated one-dimensional (1D) anode catalyst, the as-obtained PdCuTe NWs shows high specific/mass activity of 7.9 mA cm-2 and 3872.6 mA mg-1 for the ethylene glycol (EG) oxidation reaction, being 3.4 and 4.2-fold enhancement than commercial Pd/C, respectively. Moreover, the ternary PdCuTe nanowires also display excellent stability with less activity degradation after long-term electrochemical tests. Combining physicochemical characterizations and electrochemical results, we found that the 1D Te NWs template was significant for promoting the electrocatalytic activity of PdCuTe NWs, because such nanowire template was the key, leading to the attachment of active PdCu nanoparticles which successfully exposed abundant active sites and contributed to large promotion of electrocatalytic performances. This work highlights the utilization efficiency improvement via morphology design for the promotion of electrocatalytic performances.

Ultra-stable Electrochemical Sensor for Detection of Caffeic Acid Based on Platinum and Nickel Jagged-Like Nanowires.

Electrochemical sensors have the high sensitivity, fast response, and simple operation for applications in biological, medical, and chemical detection, but limited by the poor stability and high cost of the electrode materials. In this work, we used PtNi lagged-like nanowire for caffeic acid (CA) electrochemical detection. The removal of outer layer Ni during reaction process contributed to the rehabilitation of active Pt sites at the surface, leading to the excellent electrocatalytic behavior of CA sensing. Carbon-supported PtNi-modified glassy carbon electrode (PtNi/C electrode) showed a broad CA detecting range (from 0.75 to 591.783 µM), a low detection limit (0.5 µM), and excellent stability. The electrode preserved high electrocatalytic performance with 86.98% of the initial oxidation peak current retained after 4000 potential cycles in 0.5 mM caffeic acid solution. It also demonstrates excellent anti-interference capability and is ready for use in the real sample analysis.

One-pot fabrication of Nitrogen-doped graphene supported binary palladium-sliver nanocapsules enable efficient ethylene glycol electrocatalysis.

Fuel cells hold great potential of replacing traditional fossil fuel to alleviate the energy crisis and increasing environmental concerns. Although great progresses have been achieved over decades, the sluggish reaction kinetics and poor durability of electrocatalysts in fuel cells have been the decisive bottleneck that limited their practical applications. Herein, we focus on the design and development of cost-efficient anode electrocatalysts for fuel cells and report the successful creation of an advanced class of N-doped graphene (NG) supported binary PdAg nanocapsules (PdAg NCPs). The well-defined nanocatalysts with highly open structure exhibit greatly improved electrocatalytic performances for ethylene glycol oxidation reaction (EGOR). In particular, the optimized PdAg NCPs/NG show the mass and specific activities of 6118.3 mA mg-1 and 13.8 mA cm-2, which are 5.8 and 6.9 times larger than those of the commercial Pd/C catalysts, respectively. More importantly, such PdAg NCPs/NG can also maintain at least 500 potential cycles with limited catalytic activity attenuation, showing an advanced class of electrocatalysts for fuel cells.

3D hollow nanoflowers assembled by ultrathin molybdenum-nickel phosphide nanosheets as robust electrocatalysts for oxygen evolution reaction.

Designing cost-efficient and durable electrocatalysts toward oxygen evolution reaction (OER) has been of vital significance for the commercial development of various renewable energy systems. Herein, we report the construction of a new class of 3D hollow nanoflower catalysts that assembled by ultrathin nickel-molybdenum phosphide nanosheets. Owing to the increased electronic and ion transport channels, the heteroatom doping, and synergistic effects from the interconnected compositions, the newly-generated 3D MoNiP hollow nanoflowers display superior OER activity than that of Ir/C. And the optimized Mo1Ni1P hollow nanoflowers (Mo1Ni1P HNFs) can afford a current density of 10 mA cm-2 at the overpotential of 275 mV in 1.0 M KOH solution. More importantly, the resultant Mo1Ni1P HNFs also display excellent stability with negligible activity and morphology decay. This work provides insights for the utilization of earth-abundant and highly efficient electrocatalysts via rationally designing the morphology of electrocatalysts.

Self-supported nickel-cobalt nanowires as highly efficient and stable electrocatalysts for overall water splitting.

The development and design of highly active and stable electrocatalysts based on cheap and Earth-abundant materials is critically important to enable water splitting as a desirable renewable energy source. Herein, we fulfill the significant electrochemical water splitting enhancement in both electrocatalytic activity and durability by constructing self-supported nickel-cobalt nanowire catalysts with abundant oxygen vacancies. Specifically, the rich oxygen vacancies can largely promote the oxygen evolution reaction (OER) activity of optimal Ni1Co1O2 NWs with a relatively low overpotential of 248 mV to drive a current density of 10 mA cm-2. More significantly, after the phosphorization of Ni1Co1O2 NWs, the resultant Ni1Co1P NWs can also display excellent electrocatalytic hydrogen evolution reaction (HER) performances with an overpotential of only 101 mV to achieve a current density of 10 mA cm-2. Furthermore, benefiting from the unique 1D nanowire structure, the synergistic effect, and the optimal Gibbs free energy for hydrogen evolution evolved from the phosphorization, the Ni1Co1O2 NWs//Ni1Co1P NWs couple is thus highly active and stable for overall water electrolysis with a low voltage of 1.58 V at 10 mA cm-2, showing extraordinary promise for practical overall water splitting electrolysis.

Facile construction of ultrafine nickel-zinc oxyphosphide nanosheets as high-performance electrocatalysts for oxygen evolution reaction.

Realizing the synthesis of highly efficient electrocatalysts for water splitting is generally regarded as a significant section in the field of renewable energy conversion and storage but still an intriguing challenge. Here, a series of transition metal oxyphosphides with ultrafine nanosheet structure have been successfully created as high-performance electrocatalysts for oxygen evolution reaction (OER). Taking advantages of the abundant surface defects, modified electronic effects, as well as the high surface active areas, we herein successfully construct a novel class of highly-efficient electrocatalysts, and the resultant NiZn oxyphosphide nanosheets (NiZnP NSs) can exhibit relatively low overpotentials of 290 and 332 mV to achieve the current densities of 10 and 50 mA cm-2 for OER, respectively, outperforming most of non-noble metal electrocatalysts. More impressively, such NiZnP NSs can also retain high catalytic activity with negligible composition and structure variations after long-term electrochemical test. This work provides prospects to construct highly efficient, earth abundant, and ultra-durable two-dimensional (2D) electrocatalysts for water splitting.

Phosphorus-doped cobalt-iron oxyhydroxide with untrafine nanosheet structure enable efficient oxygen evolution electrocatalysis.

Although explosive progresses have been achieved in the field of water splitting, the design and development of stable and inexpensive electrocatalysts for oxygen evolution remain a formidable challenge. Herein, the cost-efficient two dimensional (2D) phosphorus-doped CoFe oxyhydroxide nanosheets (denoted as CoFeP NSs) are successfully engineered and showing exceptional oxygen evolution reaction (OER) activity and chemical stability in 1 M KOH solution. This unique 2D nanosheet structure facilitates the mass transfer and electron transport, resulting in the remarkable OER activity that delivers a current density of 10 mA cm-2 at a low overpotential of 305 mV with an ultra-small Tafel slope 49.6 mV/dec. More significantly, the doped P also plays a vital role in modulating the surface active sites, leading to the substantial enhancement of electrocatalytic performances. Our study provides a facile one-pot method for the successful fabrication of 2D P-doped CoFe NSs which display superior electrocatalytic performance, shedding great promise for environment and energy-related fields.

Sophisticated Construction of Binary PdPb Alloy Nanocubes as Robust Electrocatalysts toward Ethylene Glycol and Glycerol Oxidation.

The design of nanocatalysts by controlling pore size and particle characteristics is crucial to enhance the selectivity and activity of the catalysts. Thus, we have successfully demonstrated the synthesis of binary PdPb alloy nanocubes (PdPb NCs) by controlling pore size and particle characteristics. In addition, the as-obtained binary PdPb NCs exhibited superior electrocatalytic activity of 4.06 A mg-1 and 16.8 mA cm-2 toward ethylene glycol oxidation reaction and 2.22 A mg-1 and 9.2 mA cm-2 toward glycerol oxidation reaction when compared to the commercial Pd/C. These astonishing characteristics are attributed to the attractive nanocube structures as well as the large number of exposed active areas. Furthermore, the bifunctional effects originated from Pd and Pb interactions help to display high endurance with less activity decay after 500 cycles, showing a great potential in fuel cell applications.

Ethylene Glycol Electrooxidation Based on Pentangle-Like PtCu Nanocatalysts.

The research of active and stable electrocatalysts toward liquid-fuel oxidation reaction is of great significance for the large-scale commercialization of fuel cells. Although extensive efforts have been devoted to pursuing high-performance nanocatalysts for fuel cells, both the high cost and sluggish reaction kinetics have been two major drawbacks that limited its commercial development. In this regard, we demonstrated a facile solvothermal method for the syntheses of an advanced class of PtCu nanocatalysts with a unique pentangle-like shape. By combining the merits of a highly active surface area as well as the synergistic and electronic effects, the as-prepared pentangle-like Pt3 Cu nanocatalysts showed superior electrocatalytic activity towards ethylene glycol oxidation with a mass and specific activities of 5162.6 mA mg-1 and 9.7 mA cm-2 , approximately 5.0 and 5.1 times higher than the commercial Pt/C, respectively. More significantly, the Pt3 Cu pentangle also showed excellent long-term stability with less activity decay and negligible changes in structure after 500 cycles, indicating another class of anode catalysts for fuel cells and beyond.