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Heterogeneous catalysts based on Hg are found to be highly active for the acetylene hydration reaction with a very high yield of acetaldehyde, but severe toxicity limits its application. Herein, HEDP was selected as a polydentate phosphonate ligand to synthesize novel green Cu-based catalysts by a simple impregnation method. The prepared catalyst with the best ratio of Cu/ligand of 1 : 1 and 4 wt% Cu loading can achieve >82.9% selectivity of the aldehyde with 99% conversion of acetylene after 8 h compared to the ligand-free catalyst. The effect of the ligand and the active component on the catalytic performance was evaluated in detail by several characterization methods. XRD, TPR, and HRTEM coupled with EDS analysis revealed that the introduction of HEDP could enhance the dispersion of Cu species and decrease the particle sizes of Cu. XPS indicated strong interaction of the coordination compound formed by the coordination of Cu2+ with HEDP molecules, which effectively inhibited the reduction of Cu ions during the reaction process. TGA revealed that this complex could inhibit the coking deposition produced during the reaction. The novel perspective will provide the potential of using HEDP as a metal chelating agent to stabilize the active components and increase the dispersion for the heterogeneous catalyst.

Atomically dispersed metal catalysts are promising candidates for the oxygen reduction reaction (ORR) and for achieving efficient energy conversion. However, rational design of single atom catalysts (SACs) with high-efficiency ORR catalytic activity and superior stability is still crucial yet challenging. Herein, an in situ gas-foaming methodology is presented for constructing single Fe atoms dispersed on a N, S-codoped (FeSA/NSC) hierarchically ordered porous carbon (HOPC) framework via one-step pyrolysis of dopamine (DA)/Fe3+ complexes and thiourea in SBA-15 channels. HOPC structures (facilitating active site access and mass transfer) and optimized FeN4S2 catalytic centers make FeSA/NSC exhibit high ORR activity with a half-wave potential (E1/2) of 0.91 V, fuel selectivity and long-term stability (3 mV negative shift after 5000 potential cycles) in 0.1 M KOH. It even shows comparable ORR catalytic activity (E1/2 = 0.78 V) to the Pt/C catalyst in acidic electrolytes. As the air electrode in zinc–air batteries, FeSA/NSC demonstrates superior power density, long-term discharge stability and specific capacity to the commercial Pt/C catalyst. Thus, FeSA/NSC is a promising non-platinum-group metal ORR catalyst for the ORR and application in zinc–air batteries.

Nanoporous PdCu (NP-PdCu) was prepared by the dealloying strategy from a PdCuAl ternary alloy precursor and characterized systematically using SEM, TEM, XRD, and XPS. NP-PdCu was demonstrated to be a competent self-supported heterogenous catalyst for Suzuki–Miyaura cross-coupling, affording a series of synthetically valuable biaryl compounds in good to excellent yields. This catalyst could be easily separated from the product via centrifugation and reused several times without obvious loss of catalytic performance.

Electrocatalytic water splitting via hydrogen evolution reaction (HER) represents one of promising strategies to gain hydrogen energy. In current work, self-supporting Co0.85Se nanosheets network anchored on Co plate (Co0.85Se NSs@Co) is fabricated by employing easily tailorable Co metal plate as the source conductive substrate. The scalable dealloying and hydrothermal selenization strategy was employed to build one layer of three dimensional interlinking Co0.85Se nanosheets network on the surface of Co plate. Benefiting from bulky integrated architecture and rich active sites, the as-made Co0.85Se NSs@Co exhibits superior electrocatalytic activity and long-term catalytic durability toward HER. It only requires lower overpotentials of 121 and 162 mV to drive the current density of 10 mA·cm−2 for hydrogen evolution in 0.5 M H2SO4 and 1 M KOH solution. Especially, no evident activity decay occurs upon 1,500 cycles or continuous test for 20 h at 10 mA·cm−2 in both acidic and alkaline electrolytes. With the merits of exceptional performances, scalable production, and low cost, the self-supporting Co0.85Se NSs@Co holds prospective application potential as stable and binder-free electrocatalysts for hydrogen generation in a wide range of electrolyte.

Zr-modified ZSM-5 zeolite was successfully prepared, and Zn/Zr-ZSM-5 was employed as a catalyst for the acetylene hydration reaction. High catalytic activity, above 96% C2H2 conversion, was achieved at 260 °C with a feed reactant ratio of H2O/C2H4 = 4 and a GHSV of 90 h−1. To understand the influence of zirconium addition in the zeolite, Fourier-transform infrared spectroscopy, X-ray diffraction, surface texture analysis (BET method), transmission electron microscopy, temperature programmed desorption of NH3, temperature programmed reduction by hydrogen and X-ray photoelectron spectroscopy techniques were used. The incorporation of zirconium in the zeolite enhanced Zn metal dispersion and metal–support interactions. Moreover, an enhanced concentration of weak acid sites and active catalytic sites were found to be responsible for the high catalytic activity of Zn/Zr-ZSM-5 for the acetylene hydration.

A series of Zn–Cu bimetallic catalysts were prepared and used as catalysts for acetylene hydration in our study, and the influence of a copper additive on the performance of zinc catalysts was studied in detail. The activity test results indicate that the addition of copper improved the activity and stability of the bimetallic catalysts. The best catalytic performance was obtained over a Zn–10Cu/MCM catalyst, which gave 98% acetylene conversion. The catalysts were characterised via temperature-programmed reduction, low-temperature N2 adsorption/desorption, X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. Analysis results indicate that the Cu interacted synergistically with Zn species and prevented Zn species loss during the reaction, thereby improving the catalytic activity and stability of the bimetallic catalysts for the hydration of acetylene to acetaldehyde.

The design and fabrication of highly active and durable catalysts for the ammonia borane (AB) hydrolysis has been one of significant issues in the application of green and economic hydrogen energy. Nanoporous (NP) PtCo/Co3O4 composites are straightforwardly fabricated by selectively etching Al atoms followed by removing Co atoms from the PtCoAl precursor alloy. By controlling the second-step dealloying, the NP-PtCo/Co3O4 composites evolved into pure nanoporous structure with Co3O4 nanosheets on the surface gradually disappeared as well different Pt/Co ratios resulted. Compared with NP-Pt and pure Co3O4 catalysts, the NP-PtCo/Co3O4 composites with different Pt/Co ratios exhibit markedly enhanced catalytic activity for the hydrolysis of AB. NP-Pt40Co60 composite with some Co3O4 nanosheets anchored on the surface shows the higher catalytic activity compared to other several samples with different Pt contents, exhibiting a high initial turnover frequency of 131mol H2 min-1 (mol Pt)-1. Meanwhile, the recyclability tests indicate that NP-Pt40Co60 composite retained 65% of the initial catalytic activity after the fifth run of hydrolysis. Therefore, the high catalytic activity and good durability render the as-made composite as a powerful catalyst candidate for the hydrolytic dehydrogenation of AB in the practical applications.

Intermetallics have attracted considerable research interests in a variety of electrocatalysis reactions due to their specific activity, selectivity, and stability arising from more severe alternation of electronic structure than substitutional alloys. Herein, we report one free-standing trimodal porous β1-NiZn intermetallic and Ni heterostructure on Ni foam (TMP NiZn-Ni/NF) for hydrogen evolution reaction (HER) via electrochemical water-alkali splitting through one convenient and scalable dealloying strategy. Benefitting from high density reactive sites and fluent mass transfer as a result of trimodal porous architecture and strong electronic modulation from NiZn intermetallic, TMP NiZn-Ni/NF primely overcomes the sluggish hydrogen evolving kinetics with superior catalytic performances comparable to Pt/C and many other reported similar electrocatalysts. TMP NiZn-Ni/NF only required the low overpotential of 233 mV at high rate of 600 mA cm−2 with the small Tafel slope at 47.3 mV dec−1 in 1.0 M KOH solution. TMP NiZn-Ni/NF also exhibits exceptional catalytic durability toward HER with almost no current loss under the overpotential of 100 mV for 50 h. Theoretical calculations reveal that β1-NiZn intermetallic itself has low Gibbs free energy for H adsorption (ΔGH*), while it can also greatly decrease the ΔGH* of heterojuncted Ni. This work presents one powerful and scalable protocol to screen self-supporting nonprecious intermetallic nanocatalysts with high density active sites and outstanding catalytic efficiency.

Polyoxymethylene dimethyl ethers (PODEn) are ideal blending components of diesel oil. However, there are few studies to identify the reaction path of PODEn synthesis, which is essential in understanding the reaction. In this work, the reaction path of PODEn synthesis from methanol and paraformaldehyde on the Al-MCM-41 zeolite was studied by density functional theory calculation and experiment. The structures of intermediates and transition states of PODEn synthesis were designed and optimized. The three possible reaction paths were analyzed by comparing the Gibbs free energy barriers in the calculation and the product distribution in the experiment. The results showed that paraformaldehyde is decomposed into formaldehyde first. Formaldehyde and methanol react to form a hemiacetal intermediate. Then methanol reacts with hemiacetal to form dimethoxymethane. This step has the highest free energy barrier (121.2 kJ·mol−1), which is the rate-determining step. The long-chain PODEn is formed by chain growth from PODEn-1 and formaldehyde.

Nanoporous (NP) PdCu alloy is easily fabricated by dealloying PdCuAl ternary alloy in dilute sulfuric acid. Selectively dissolving Al from PdCuAl alloy generates the three-dimensional uniform nanosponge architecture with narrow ligament size distribution. Benefitting from the unique nanoporous architecture and the alloying effect, the as-made NP-PdCu exhibits outstanding sensing performance towards the detection of hydrogen peroxide (H2O2) and glucose. Compared with NP-Pd and commercial Pd/C catalysts, the NP-PdCu alloy presents high sensitivity, wide linear range of 0.1–2.0 mM, low detection limit of 2.1 μM, and long-term stability toward H2O2 detection. In addition, the NP-PdCu can efficiently detect glucose in a wide concentration range (1–30 mM) with the low detection limit of 1.9 μM. Moreover, the NP-PdCu exhibits good anti-interference toward ascorbic acid, uric acid, and dopamine. Characterized by easy preparation, unique electrocatalytic activity, and high structure stability, the NP-PdCu alloy possesses great application prospect to construct platform for electrochemical sensing.

A graphene-encapsulated Mn3O4/Ag nanocomposite is fabricated through a simple dealloying method to obtain Mn3O4 octahedra embedded in a nanoporous Ag network followed by encapsulation by graphene nanosheets. Upon selectively dissolving the Al atoms from the MnAgAl alloy, the residual Ag atoms assemble to form a well-conductive network; meanwhile the Mn atoms undergo natural oxidation to form Mn3O4 octahedra that travel through the Ag network. The positively charged Mn3O4/Ag composite modified by aminopropyltrimethoxysilane was enwrapped by negatively charged graphene oxide nanosheets followed by a reduction process. Owing to the combination of Mn3O4/Ag well-encapsulated in graphene nanosheets, the as-made composite exhibited significantly enhanced lithium storage performances with much higher reversible capacity and superior cycling stability as compared with the pure Mn3O4 and Mn3O4@rGO. In particular, the Mn3O4/Ag@rGO composite shows high reversible capacity retention of 971.5 and 763.5 mA h g−1 at 300 and 1000 mA g−1 over 200 cycles, respectively. In addition, it shows excellent rate capability even when continuously cycled at high current densities of 1000, 2000, and 3000 mA g−1. With the advantages of excellent performance and facile preparation, the as-made Mn3O4/Ag@rGO composite shows promising application potential as an anode material in lithium ion batteries.

The development of high efficiency, earth-abundant and stable catalysts is of great significance for hydrogen evolution reaction (HER). In this work, the two-dimensional NiCoO2–NiCoP nanosheets with conductive Ni matrix have been developed through simple dealloying strategy to fabricate NiCoO2/Ni precursor followed by partial phosphorization under mild conditions. The synergistic effect between NiCoP and NiCoO2 in the nanosheets is beneficial to boost abundant active sites while the conductive Ni matrix gives rise to the fluent electron transfer for the HER. Compared with the NiPx and CoPx, the as-prepared NiCoO2–NiCoP/Ni nanocomposite exhibits outstanding catalytic activity and structure stability toward HER in 1 M KOH solution. A lower overpotential of 81 mV is sufficient for NiCoO2–NiCoP/Ni nanocomposite to reach the current density of 10 mA cm−2. Especially, NiCoO2–NiCoP/Ni exhibits superior catalytic durability with almost no activity decay for long-term tests over 30 h corresponding to the current density of 10 mA cm−2. With the high catalytic efficiency and excellent durability, the NiCoO2–NiCoP/Ni nanocomposite provides promising application prospects in the field of HER.

We descried a mild route to the straightforward fabrication of nanoporous ruthenium (NP–Ru) by one−step mild etching of RuAl alloy. NP–Ru consisted of an interconnected nanoscaled ligaments with bicontinuous hollow channels extending in all three dimensions. The resulting NP–Ru shows high catalytic activity at room temperature and a long life time toward hydrolysis of ammonia borane (AB). It is also found that NP–Ru has superior reusability as well the recyclability with 67% of their initial catalytic activity retained even after five runs. Additionally, the activation energy of the hydrolysis of AB over NP–Ru was evaluated based on the kinetic studies depending on the reaction temperature. The effect of catalyst concentration was also explored on the reaction rate of hydrolysis of AB, indicating that the hydrolysis reaction is the first–order reaction with respect to the concentration of NP–Ru.

Nanoporous (NP) PdZr alloy with controllable bimetallic ratio is successfully fabricated by a simple dealloying method. By leaching out the more reactive Al from PdZrAl precursor alloy, NP–PdZr alloy with smaller ligament size was generated, characterized by the nanoscaled interconnected network skeleton and hollow channels extending in all three dimensions. Upon voltammetric scan in acid solution, the dissolution of surface Zr atoms generates the highly active Pd–Zr surface alloy with a nearly pure Pd surface and Pd–Zr alloy core. The NP–Pd 80 Zr 20 surface alloy exhibits markedly enhanced specific and mass activities as well as higher catalytic stability toward oxygen reduction reaction (ORR) compared with NP–Pd and the state–of–the–art Pt/C catalysts. In addition, the NP–Pd 80 Zr 20 surface alloy shows a better selectivity for ORR than methanol in the 0.1 M HClO 4 and 0.1 M methanol mixed solution. X–ray photoelectron spectroscopy and density functional theory calculations both demonstrate that the weakened Pd–O bond and improved ORR performances in turn depend on the downshifted d–band center of Pd due to the alloying Pd with Zr (20 at.%). The as–made NP–PdZr alloy holds prospective applications as a cathode electrocatalyst in fuel–cell–related technologies with the advantages of superior overall ORR performances, unique structure stability, and easy preparation.

Nanoporous (NP) PtRu alloys with three different bimetallic components were straightforwardly fabricated by dealloying PtRuAl ternary alloys in hydrochloric acid. Selective etching of aluminum from source alloys generates bicontinuous network nanostructures with uniform size and structure. The as-made NP-PtRu alloys exhibit superior catalytic activity toward the hydrolytic dehydrogenation of ammonia borane (AB) than pure NP-Pt and NP-Ru owing to alloying platinum with ruthenium. The NP-Pt70 Ru30 alloy exhibits much higher specific activity toward hydrolytic dehydrogenation of AB than NP-Pt30 Ru70 and NP-Pt50 Ru50 . The hydrolysis activation energy of NP-Pt70 Ru30 was estimated to be about 38.9 kJ mol(-1) , which was lower than most of the reported activation energy values in the literature. In addition, recycling tests show that the NP-Pt70 Ru30 is still highly active in the hydrolysis of AB even after five runs, which indicates that NP-PtRu alloy accompanied by the network nanoarchitecture is beneficial to improve structural stability toward the dehydrogenation of AB.

Nanoporous gold (NPG) catalysts with different types of oxide residues are fabricated by a simple electrochemical dealloying method with the aim of exploring the origin of high catalytic activity on unsupported gold catalyst systems. By leaching out the reactive components from AuCu and AuAl alloys, unsupported NPG with so-called active CuO and inert Al2O3 residues were generated, characterized by an open interconnected network architecture with a narrow ligament size distribution. The NPG catalyst with inert Al2O3 residues shows a CO reaction rate and turnover frequency similar to those on NPG with active CuO residues under the same measurement conditions. In comparison, NPG(Cu) with active CuO residues exhibits better catalytic durability for CO oxidation than NPG(Al) catalyst, possibly because of its stabilization for nanoporous architecture. Experimental observations suggest that the so-called active or inert oxide residues in the as-made NPG catalysts have almost no effect on the intrinsic catalytic activity of gold, whereas metallic gold plays the catalytic role in this unsupported NPG system.

A support-free hierarchical nanoporous (NP) Cu@Cu2O composite is easily fabricated by dealloying Cu5Al95 alloy in dilute NaOH solution. This bulk material has a support-free spongy structure composed of three-dimensional interconnected ligaments and open pore channels with multimodal pore size distributions. The NP-Cu@Cu2O catalyst exhibits high activity, good chemoselectivity, and excellent recyclability toward one-pot transfer hydrogenation reactions of diverse nitroarenes to anilines. NP-Cu@Cu2O can effectively activate ammonia borane under mild conditions and complete the transfer hydrogenation reactions with high yields within a short time period of 5 min Cu2O formed at the nanoporous surface is proposed to be the actual active site causing this advanced performance. The main reaction intermediates were successfully separated and characterized, and a plausible condensation mechanism has been proposed for nitro reduction.

Hierarchical nanoporous (HNP) PtTi alloy with multimodal size distributions and controllable bimetallic ratio is successfully fabricated by a simple two–step dealloying process. The as–prepared HNP–Pt 75 Ti 25 alloy consists of interconnected bimodal nanoporous architecture with two order ligament/pore size distributions and interconnected hollow channels extending in all three dimensions. Compared with the NP–Pt and commercial Pt/C catalysts, HNP–Pt 75 Ti 25 alloy exhibits markedly enhanced electrocatalytic activities for oxygen reduction reaction (ORR) with superior catalytic durability besides the higher specific and mass activities. X–ray photoelectron spectroscopy and density functional theory calculations demonstrate that alloying Pt with Ti (25 at.%) could bring favorable electronic perturbation with the downshifted d–band center of Pt, leading to the weakened Pt–O and Pt–OH bond as well as the improved ORR performances. The excellent electrocatalytic performances for ORR and the facile preparation render HNP–Pt 75 Ti 25 alloy attractive as promising cathode electrocatalysts in proton exchange membrane fuel cells.

Nanoporous (NP) PtPd alloys with three different bimetallic ratios are straightforwardly fabricated by one–step mild dealloying of PtPdAl precursor alloys in alkaline solution. These as–prepared PtPd alloys are comprised of nanoscaled bicontinuous network skeletons and interconnected hollow channels extending in all three dimensions with uniform ligament size around 5 nm. Compared with commercial Pt/C, NP–Pd, and NP–Pt catalysts, NP–PtPd alloys exhibit superior electrocatalytic activities toward oxygen reduction reaction (ORR) with much higher specific and mass activities. More importantly, NP–PtPd alloys also show superior structure stability with almost no ORR activity loss upon long–term potential scan compared with Pt/C catalyst. The ORR performance follows the order of NP–Pt 75 Pd 25 > NP–Pt 20 Pd 80 > NP–Pt 50 Pd 50 > NP–Pt > Pt/C > NP–Pd. NP–PtPd alloys hold great application potential as cathode catalysts in proton exchange membrane fuel cells with the advantages of facile preparation, high–yielding, and superior ORR activities and structure durability.

Nanoporous PtFe alloys with two different bimetallic ratios are fabricated by selectively dealloying PtFeAl ternary alloys, characterized by nanoscaled bicontinuous network skeleton with interconnected hollow channels extending in all three dimensions. The reactive components in PtFeAl ternary alloy were sequentially leached out in a highly controllable manner, generating nanoporous architecture with different bimetallic ratios and the typical ligament size as small as 5 nm. These nanoporous PtFe alloys exhibit much enhanced electrocatalytic activity for oxygen reduction reaction compared with the PtFe/C and Pt/C catalysts. The specific and mass activities for oxygen reduction follow the order of nanoporous Pt75Fe25 > nanoporous Pt55Fe45 > PtFe/C > Pt/C. In the absence of any catalyst support, the structure stability of nanoporous PtFe alloys is greatly enhanced with less loss of the electrochemical surface area and the oxygen reduction activity upon long-term potential scan tests compared with PtFe/C and Pt/C catalysts. The as-made nanoporous PtFe alloys thus hold great application potential as promising cathode electrocatalyst in proton exchange membrane fuel cells with the advantages of easy preparation along with superior oxygen reduction activity and durability.

Hierarchical nanoporous platinum-copper (hnp-PtCu) alloy nanoflowers with bimodal pore/ligament size are easily fabricated by selectively dissolving Al atoms and part of Cu atoms from PtCuAl ternary alloy. The dealloyed samples consist of cross-linking porous nanoflowers with interconnected network skeleton and hollow channels penetrated. Hnp-PtCu alloy nanoflowers with different compositions exhibit dramatically enhanced catalytic activities toward the hydrolysis of ammonia borane (AB) compared with their monometallic components. The hnp-Pt35Cu65 alloy shows superior catalytic performance than the other hnp-PtCu catalysts with an initial much higher turnover frequency of 108 mol H2 min-1 (mol Pt)-1. Moreover, the hnp-Pt35Cu65 displays excellent structure stability even after the five runs for the AB hydrolysis. The as-made hnp-PtCu catalysts hold promising application potential toward the AB hydrolysis with the advantages of facile preparation, high yielding, superior catalytic activity, and high structure durability.

Nanoporous PdFe (NP-PdFe) alloy with uniform structure size and controllable bimetallic ratio was easily fabricated by one-step mild dealloying from PdFeAl precursor alloy. NP-PdFe consisted of nanoscaled interconnected network skeleton with bicontinuous hollow channels extending in all three dimensions. Compared with NP-Pd and commercial Pt/C catalysts, the NP-PdFe exhibits superior electrocatalytic activity for oxygen-reduction reaction (ORR) with enhanced specific and mass activities. Electrocatalytic measurements indicated that NP-PdFe possesses higher catalytic durability than Pt/C with the less loss of ORR activity and electrochemical active surface area upon long term potential scan. NP-PdFe alloy also shows higher methanol tolerance relative to Pt/C catalyst. XPS and DFT calculations suggest that the downshift of Pd d-band center after alloying with Fe makes favorable reaction kinetics for ORR with decreased adsorption energy of O and OH on Pd surface.

Nanoporous (NP) PtAu alloy is easily fabricated by a simple and general dealloying method. Characterized by three-dimensional nanospongy architecture with a typical dimension around 5 nm, the as-prepared NP-PtAu alloy shows superior sensing performance towards glucose and hydrogen peroxide (H2O2) with highly sensitive response compared with commercial Pt/C and NP-Pt catalysts. Importantly, NP-PtAu exhibits excellent amperometric durability and long-term stability for H2O2 and glucose. After coating additional nafion on the working electrode, NP-PtAu shows a good anti-interference towards ascorbic acid, uric acid, and dopamine during glucose detection. NP-PtAu alloy holds great application potential for electrochemical sensing with simple preparation, high catalytic activity, and high structure stability.

Nanoporous (NP) PdCu alloys with three different bimetallic ratios are fabricated by selectively dealloying PdCuAl ternary alloys in sulfuric acid solution. Electron microscopy and X-ray diffraction characterizations demonstrate that selective etching of Al from ternary PdCuAl source alloys in acid medium generates three-dimensional bicontinuous ligament-pore nanostructures with a single-phase face-centered-cubic crystalline structure. NP-PdCu alloys show superior electrocatalytic activity and structure stability toward oxygen reduction reaction (ORR) compared with the commercial Pt/C catalyst. The specific and mass activities for ORR follow the order of NP-Pd50Cu50 > NP-Pd75Cu25 > NP-Pd30Cu70 > Pt/C. It is found that among three PdCu samples NP-Pd50Cu50 exhibits the highest methanol tolerance and catalytic durability for ORR. These experimental observations indicate that incorporation of 50 at.% Cu into Pd accompanied with the network nanoarchitecture is beneficial to maximize the ORR performances of Pd.

A nanoporous (NP) PdCo alloy with uniform structure size and controllable bimetallic ratio was fabricated simply by one-step mild dealloying of a PdCoAl precursor alloy. The as-made alloy consists of a nanoscaled bicontinuous network skeleton with interconnected hollow channels that extend in all three dimensions. With a narrow ligament size distribution around 5 nm, the NP PdCo alloy exhibits much higher electrocatalytic activity towards the oxygen-reduction reaction (ORR) with enhanced specific and mass activities relative to NP Pd and commercial Pt/C catalysts. A long-term stability test demonstrated that NP PdCo has comparable catalytic durability with less loss of ORR activity and electrochemical surface area than Pt/C. The NP PdCo alloy also shows dramatically enhanced catalytic activity towards formic acid electrooxidation relative to NP Pd and Pd/C catalysts. The as-made NP PdCo holds great application potential as a promising cathode as well as an anode electrocatalyst in fuel cells with the advantages of superior catalytic performance and easy preparation.

Nanoporous (NP) PtNi alloy is easily fabricated through one step mild dealloying from PtNiAl source alloy. Characterized by three-dimensional nanosponge architecture with the typical dimension size as small as 3 nm, the as-made NP-PtNi alloy exhibits superior sensing performance with superior sensitivity and low detection limit toward ethanol and H2O2 as compared with state-of-the-art Pt/C catalyst due to its unique electrocatalytic activities. In particular, long-term sensing tests demonstrated that NP-PtNi alloy has distinct sensing durability with almost no activity loss upon continuous H2O2 detection for two weeks. Along with these attractive features, the as-made NP-PtNi alloy also behaves a good anti-interference toward glucose, ethanol, ascorbic acid, uric acid, and dopamine during H2O2 detection. NP-PtNi alloy shows great potential for electrochemical sensing applications.

A series of polyallene-based well-defined amphiphilic graft copolymers, poly(6-methyl-1,2-heptadiene-4-ol)-g-poly(2-(diethylamino)ethyl methacrylate) (PMHDO-g-PDEAEMA), was synthesized through the grafting-from technique. First, double-bond-containing PMH

A simple and convenient dealloying method is used to prepare nanoporous (NP) PdCr alloys with uniform ligament dimensions and controllable bimetallic ratio. The structural characterization methods demonstrate that the NP-PdCr alloy is comprised of a nanoscaled interconnected network skeleton and hollow channels extending in all three dimensions. Electrocatalytic measurements indicated that the as-made NP-Pd75Cr25 alloy exhibits superior specific and mass activities as well as higher catalytic stability toward oxygen reduction reaction compared with NP-Pd67Cr33, NP-Pd, and commercial Pt/C catalysts. X-ray photoelectron spectroscopy and density functional theory calculations both demonstrate that the weakened Pd-O bond and improved ORR performances depend on the downshifted d-band center of Pd due to the alloying of Pd with Cr (25 at%). It is expected that the as-made NP-PdCr alloy has prospective application as a cathode electrocatalyst in fuel-cell-related technologies with the advantages of superior overall ORR performances, unique structural stability, and easy preparation.

A nanoporous PdTi (NP-PdTi) alloy with uniform ligament size and controllable bimetallic ratio was easily fabricated by a one-step mild dealloying process of PdTiAl (precursor alloy). NP-PdTi consisted of an interconnected network of nanoscale ligaments with bicontinuous hollow channels extending in all three dimensions. Electrocatalytic measurements indicated that NP-PdTi had superior electrocatalytic activity in the oxygen reduction reaction (ORR) with enhanced specific and mass activities as well higher methanol tolerance relative to Pt/C. Interestingly, NP-PdTi showed higher catalytic durability than Pt/C with a lower decrease in the ORR activity and electrochemical surface area of the metal upon 5000 potential cycles in an acidic solution. DFT calculations demonstrated that alloying Pd with Ti could bring favorable electronic perturbation with the downshifted d-band center of Pd, leading to a weakened PdO bond and improved ORR performance. The excellent electrocatalytic performance in ORR renders NP-PdTi alloys attractive as efficient cathode electrocatalysts in fuel-cell-related technologies.

Nanoporous (NP) PtCo and PtNi alloy ribbons with predetermined bimetallic compositions are easily fabricated by one step of mild dealloying, which are characterized by uniform three-dimensional bicontinuous network architecture with the ligament size as small as 3 nm. Compared with E-TEK Pt/C catalyst, the as-made NP-PtCo(Ni) alloys exhibit superior specific activity with the lower peak potential and enhanced CO-tolerance toward methanol electrooxidation. More importantly, these nanomaterials also show much higher structure stability with little loss of the electrochemical surface area of Pt upon 5000 potential cycles in acid solution. X-ray photoelectron spectroscopy and DFT calculations revealed that alloying with Co or Ni modifies the electronic structure of Pt with the downshift of Pt d-band center, thus resulting in the improved methanol oxidation activity and decreased CO poisoning.

It is of critical importance to design and fabricate highly active and durable oxygen reduction reaction (ORR) catalysts for the application of proton exchange membrane fuel cells (PEMFCs). By a simple two-step dealloying process, the active components in a Pt/Ni/Al ternary alloy were sequentially leached out in a highly controllable manner, generating a novel nanoporous surface alloy structure. Characterized by an open bicontinuous spongy morphology, the resulting nanostructure is interconnected by ∼3 nm diameter ligaments which are comprised of a Pt/Ni alloy core and a nearly pure Pt surface. In the absence of any catalyst support, these nanoporous surface alloys show much enhanced durability and electrocatalytic activity for ORR as compared to the commercial Pt/C catalyst. At a high potential, such as 0.9 V versusRHE, nanoporous Pt/Ni surface alloys show a remarkable specific activity of 1.23 mA cm−2. These nanomaterials thus hold great potential as cathode catalysts in PEMFCs in terms of facile preparation, clean catalyst surface, and enhanced ORR activity and durability.

Nanoporous platinum was fabricated by a simple dealloying method. Electron microscope characterizations show that selectively etching Al from PtAl alloy precursors in alkali or acid solution can both easily prepare three-dimensional bicontinuous network nanostructures of Pt. The resulted nanostructure exhibited much enhanced catalytic performance towards methanol electrooxidation compared with commercial Pt/C catalyst. More importantly, CO stripping and potentiostatic tests demonstrated that nanoporous Pt has much higher long-term catalytic stability and CO resistance than the Pt/C catalyst. Copyright © 2011 VBRI press.

We describe a general strategy to fabricate a new type of nanoporous core/shell structured bimetallic nanocomposites with controllable metal components. Nanoporous copper (NPC) obtained by dealloying Cu/Al alloy is used as both reducing agent and three-dimensional substrate. Electron microscope and X-ray diffraction characterizations demonstrated that a simply galvanic-replacement reaction with H(2)PtCl(6) aqueous solution can easily generate nanoporous core/shell structure with a thin Pt/Cu alloy shell and Cu (or Pt/Cu alloy) core. The morphology and crystal structure evolution of the nanocomposites are studied and discussed in detail. The as-prepared bimetallic PtCu nanocomposites show greatly enhanced catalytic activity and stability toward methanol electro-oxidation as compared with commercial Pt/C catalyst. This facile in situ preparation strategy is also suitable for large-scale production of this novel and inexpensive catalyst.

Nanoporous silver (NPS) and copper (NPC) obtained by dealloying AgAl and CuAl alloys, respectively, were used as both three-dimensional templates and reducing agents for the fabrication of nanoporous PtAg (NPS-Pt) and PtCu (NPC-Pt) alloys with hollow ligaments by a simple galvanic replacement reaction with H(2)PtCl(6). Electron microscopy and X-ray diffraction characterizations demonstrate that NPS and NPC with similar ligament sizes (30-50 nm) have different effects on the formed hollow nanostructures. For NPS-Pt, the shell of the hollow ligament is seamless. However, the shell of NPC-Pt is comprised of small pores and alloy nanoparticles with a size of similar to 3 nm. The as-prepared NPS-Pt and NPC-Pt exhibit remarkably improved electrocatalytic activities towards the oxidation of ethanol and H(2)O(2) compared with state-of-the-art Pt/C catalyst, and can be used for sensitive electrochemical sensing applications. The hierarchical nanoporous structure also provides a good microenvironment for enzymes. After immobilization of glucose oxidase (GOx), the enzyme modified nanoporous electrode can sensitively detect glucose in a wide linear range (0.6-20 mM). (C) 2011 Elsevier B.V. All rights reserved.

Nanoporous PdCu alloys (NP-PdCu) with uniform PdCu alloy ligament (~6 nm) and predetermined bimetallic ratio are prepared by selectively dealloying PdCuAl ternary alloys in an alkaline solution. NP-PdCu exhibit greatly enhanced electrocatalytic activity for formic acid and methanol oxidation compared with nanoporous Pd (NP-Pd). Moreover, the structure stability of NP-PdCu is also greatly enhanced. The electrochemical surface area of NP-PdCu is well-maintained after 10,000 potential cycles from 0.6 to 0.9 V (vs. RHE) in 0.5 M H2SO4 aqueous solution, while that of NP-Pd drops dramatically after 5000 cycles. The NP-PdCu will be promising anode catalysts for fuel cell-related technology. Keywords: Dealloying, Fuel cell, Stability

We describe the fabrication of novel PdCu bimetallic nanocomposites with hierarchically hollow structures through a simple galvanic replacement reaction using dealloyed nanoporous copper (NPC) as both a template and reducing agent. The reaction process was monitored by UV−vis absorbance spectra and X-ray diffraction (XRD), which clearly demonstrate a structure evolution from NPC precursor to a Pd-rich PdCu alloy structure upon the completion of the reaction. Structure characterization by means of transmission electron microscope (TEM) and scanning electron microscope (SEM) indicates that the replacement reaction between NPC and [PdCl4]2− solution results in a nanotubular mesoporous structure with a nanoporous shell, which is comprised of interconnected alloy nanoparticles with size around 3 nm. The resulted PdCu nanostructure shows superior activity toward oxygen reduction reaction (ORR) with a half-wave potential at 0.840 V, which is significantly better than that of the commercial Pt/C catalyst.

This study reports a facile hydrothermal method for the synthesis of monodispersed hematite (α-Fe2O3) nanodiscs under mild conditions. The method has features such as no use of surfactants, no toxic precursors, and no requirements of high-temperature decomposition of iron precursors in non-polar solvents. By this method, α-Fe2O3 nanodiscs were achieved with diameter of 50 ± 10 nm and thickness of ~6.5 nm by the hydrolysis of ferric chloride. The particle characteristics (e.g., shape, size, and distribution) and functional properties (e.g., magnetic and catalytic properties) were investigated by various advanced techniques, including TEM, AFM, XRD, BET, and SQUID. Such nanodiscs were proved to show unique magnetic properties, i.e., superparamagnetic property at a low temperature (e.g., 20 K) but ferromagnetic property at a room temperature (~300 K). They also exhibit low-temperature (

Nanoporous gold (NPG) catalysts, made by dealloying Ag/Au alloys, were found to be novel unsupported Au nanocatalysts that exhibited effective catalytic activity and high selectivity (∼99%) for the...

CeO(2) nanotubes have been synthesized with a simple solid-liquid interface reaction route in the absence of any surfactants. Although the basic reaction principles are similar, two kinds of nanotubes with completely different morphologies and structures can be generated by slightly tuning the postprocessing conditions. The first formation involves employing Ce(OH)CO(3) nanorods as both the physical and chemical templates, and the other requires layered Ce(OH)3 as an anisotropic intermediate species. During this process, NaOH and reaction temperature were demonstrated as the key factors responsible for the formation of Ce(OH)(3) intermediate and final CeO(2) nanotubes with well-defined structures. The structural details were provided by a combination of XRD, SEM, TEM, and HRTEM investigations. Catalytic measurement shows that both nanotubes are very active for CO oxidation, and at 250 degrees C, the conversion rates of CeO(2) nanotubes are 3 times higher than that of the bulk counterpart.

Nanoporous gold (NPG), a novel unsupported gold catalyst prepared by dealloying, exhibits exceptional catalytic activity for CO oxidation. Systematic studies were carried out on this new catalytic system, including the active sites of catalysts, the reaction kinetics, and activity dependence as functions of space velocity and temperature. Our results show strong evidence that metallic gold atoms on NPG are the intrinsic active sites at which the reaction of CO with O 2 occurs. The kinetic study found that the reaction rate of CO oxidation on unsupported NPG depends significantly on CO concentration but only slightly on O 2 concentration. We suggest that CO adsorption plays a decisive role in CO oxidation on NPG as the rate-limiting step. By completely ruling out the support influence, our findings provide considerable insight into the role of gold catalysts.

This approach features the combination of a Pd(0) catalyst with a Broensted acid, with a neat tuning of reactivity between dimerization and hydration.

Nanoporous (NP) PdFe alloy is easily fabricated through one step mild dealloying of PdFeAl ternary source alloy in NaOH solution. Electron microscopy characterization demonstrates that selectively dissolving Al from PdFeAl alloy generates three-dimensional bicontinuous nanospongy architecture with the typical ligament size around 5 nm. Electrochemical measurements show that the NP-PdFe alloy exhibits the superior electrocatalytic activity and durability towards hydrogen peroxide (H2O2) detection compared with NP-Pd and commercial Pd/C catalysts. In addition, NP-PdFe performs high sensing performance towards H2O2 in a wide linear range from 0.5 to 6 mM with a low detection limit of 2.1 μM. This nanoporous structure also can sensitively detect glucose over a wide concentration range (1–32 mM) with a low detection limit of 1.6 μM and high resistance against chloride ions. Along with these attractive features, the as-made NP-PdFe alloy also has a good anti-interference towards ascorbic acid, uric acid, and dopamine.

Nanoporous platinum-cobalt (NP-PtCo) alloy with hierarchical nanostructure is straightforwardly fabricated by dealloying PtCoAl alloy in a mild alkaline solution. Selectively etching Al resulted in a hierarchical three-dimensional network nanostructure with a narrow size distribution at 3 nm. The as-prepared NP-PtCo alloy shows superior performance toward ethanol and hydrogen peroxide (H2O2) with highly sensitive response due to its unique electrocatalytic activity. In addition, NP-PtCo also exhibits excellent amperometric durability and long-term stability for H2O2 as well as a good anti-interference toward ascorbic acid, uric acid, and dopamine. The hierarchical nanoporous architecture in PtCo alloy is also highly active for glucose sensing electrooxidation and sensing in a wide linear range. The NP-PtCo alloy holds great application potential for electrochemical sensing with simple preparation, unique catalytic activity, and high structure stability.