The recent development of Aurum (Au) introduced Platinum (Pt) based nanomaterials is of great significance to direct methanol fuel cell as electrocatalysts for anode reactions, due to its stability ...and anti-poisoning features. Therefore, the performance of PtAu based catalysts with different elements, atomic ratio, and morphology was studied in methanol solution to further improve its electrocatalytic activity. Furthermore, the effects of Au have aroused the researchers’ attention in Pt-based nanocatalysts. In this review, we summarize the controllable synthesis, mechanism, and catalytic performance of Au introduced Pt-based electrocatalysts such as PtAu core-shell nanostructures, PtAu dendrite, PtAu nanowires, self-supporting Au@Pt NPs, and Au@Pt star-like nanocrystals for the methanol oxidation reaction. Finally, the challenges and research directions for the future development of PtAu based catalysts are provided.
Nitrogen and fluorine dual-doped porous graphene nanosheets (NFPGNS) have been successfully synthesized as efficient bifunctional metal-free electrocatalysts for overall water splitting via a simple ...chemical-etching method. Pyridinic N doping rich configurations have been proven beneficial for the electrochemical process. The onset voltage of water splitting on the NFPGNS is lower than 1.60 V, only slightly higher than that found for Pt/C electrocatalysts. Particularly, an onset potential of 1.45 V vs. RHE on the NFPGNS for the OER is lower than some metal based electrocatalysts, involving Pt/C. DFT calculations reveal the origin of the electrocatalytic activity on the NFPGNS for the HER and OER; heteroatom-doped graphene materials modify the electron acceptor-donor properties of carbon via a synergistic coupling effect between heteroatoms. This leads to favorable electronic structures tuning the C sites around the heteroatoms, introducing a stronger adsorption strength and consequently, a lower value for the Gibbs free energy.
Mastery over the architecture and elemental distribution of metal nanocrystals at the nanoscale can effectively tailor and improve their catalytic properties. Herein, the vertex‐type‐selective growth ...of metallic nanohorns on a central nanocrystal is constructed via a one‐pot solvothermal synthesis, despite the fact that the site‐selective epitaxy of the second phase proceeds on all the vertices of the seeds. The prepared vertex‐type‐selective Pt–Cu–Rh heterogeneous nanocages (HNCs) are composed of a Rh‐decorated Pt–Cu rhombic dodecahedral nanocage and six Pt–Cu–Rh nanohorns protruding from the {100} rather than the {111} vertices of rhombic dodecahedron. Impressively, the Pt–Cu–Rh HNCs exhibit 8.1 times higher specific and 6.8 times higher mass activity toward the ethanol oxidation reaction under acidic conditions than commercial Pt/C catalysts. Besides, the peak potential for CO oxidation on Pt–Cu–Rh HNCs (370.4 mV vs SCE) is 182.0 mV more negative than that on Pt/C, indicating the dramatically enhanced CO tolerance. The excellent electrocatalytic property is attributed to the synergistic effect between Pt, Cu, and Rh components, high specific surface area of nanocages and nanohorns, as well as abundant concave/convex sites and various high‐index facets around the surface.
Pt–Cu–Rh heterogeneous nanocages (HNCs) with nanohorns protruding from the {100} rather than the {111} vertices of the central rhombic dodecahedral nanocage are prepared via a facile one‐pot solvothermal synthesis and subsequent acid treatment. The obtained Pt–Cu–Rh HNCs exhibit a superior catalytic property and CO‐poisoning tolerance toward the ethanol electro‐oxidation reaction in acidic media compared to commercial Pt/C catalysts.
Lithium−sulfur (Li−S) batteries with ultrahigh theoretical energy densities have thus far attracted significant attention as the next‐generation energy storage systems. However, the presence of the ...polysulfide shuttle effect and sluggish reaction kinetics have critically hindered their research progress. Herein, the fabrication of novel VC‐VO heterogeneous particles supported on a hierarchical porous carbon matrix (VC‐VO/HPC) is reported that regulate the disordered motion of lithium polysulfides (LiPSs); these particles can simultaneously achieve powerful anchoring, fast diffusion, and high‐efficiency conversion of LiPSs. Moreover, the in situ characterization of VC‐VO/HPC@S provides a rational inference for their phase evolution in the galvanostatic charge/discharge process. The formation of the V5S8 phase during electrochemical cycling primarily facilitates the interconversion of liquid‐phase polysulfides. Consequently, the VC‐VO/HPC@S cathodes exhibit excellent capacity performance (1484 mAh g−1 at 0.1 C) and ultrahigh cycle stability (0.045% decay rate per cycle at 5 C). The pouch cell exhibits a high energy density of 358 Wh kg−1. This approach explores the phase evolution of VC‐VO particles in an electrochemical environment and is valuable for the development of Li−S batteries with high area capacity and long cycle life.
A unique VC‐VO heterogeneous particles based on a hierarchical porous carbon matrix are successfully prepared to facilitate sulfur‐related species conversion in Li−S batteries. The electrochemical phase evolution of VC‐VO during the cycling is revealed in polysulfide‐rich conditions. Additionally, it is explored how the formation phase (V5S8) defines the polysulfide.
Rational structure and morphology design are of great significance to realize excellent Na storage for advanced electrode materials in sodium‐ion batteries (SIBs). Herein, a cube‐like core/shell ...composite of single MnS nanocubes (≈50 nm) encapsulated in N, S co‐doped carbon (MnS@NSC) with strong CSMn bond interactions is successfully prepared as outstanding anode material for SIBs. The carbon shell significantly restricts the expansion of the MnS volume in successive sodiation/desodiation processes, as demonstrated by in situ transmission electron microscopy (TEM) of one single MnS@NSC nanocube. Moreover, the in situ generated CSMn bonds between the MnS core and carbon shell play a significant role in improving the Na‐storage stability and reversibility of MnS@NSC, as revealed by in situ Raman and TEM. As a result, MnS@NSC exhibits a high reversible specific capacity of 594.2 mAh g−1 at a current density of 100 mA g−1 and an excellent rate performance. It also achieves a remarkable cycling stability of 329.1 mAh g−1 after 3000 charge/discharge cycles at 1 A g−1 corresponding to a low capacity attenuation rate of 0.0068% per cycle, which is superior to that of pristine MnS and most of the reported Mn‐based anode materials in SIBs.
A cube‐like core/shell composite of single MnS nanocubes encapsulated in N, S co‐doped carbon (MnS@NSC) with strong CSMn bond interactions is prepared successfully. As demonstrated by electrochemical tests and in situ studies, the MnS@NSC delivers high reversible capacity, excellent cycling stability, and rate capability as anode material in sodium‐ion batteries, which benefits from the sulfur‐bridged bonds and unique core/shell structure.
Despite considerable progress in the field of sustainable ammonia synthesis technologies, the sluggish kinetics of nitrogen reduction has restricted its applicability. The development of highly ...efficient photocatalysts for solar-driven nitrogen fixation remains a great challenge. In this work, we demonstrate a general synthesis strategy of using mesoporous SrTiO3 nanoparticle catalysts for nitrogen reduction through multiple defects and strain engineering. Experimental and theoretical studies show that certain number of surface defects such as oxygen vacancies were generated through a controlled hydrogenation process and the lattice strain was introduced through liquid nitrogen quenching, producing synergism in boosting the photocatalytic activity of mesoporous SrTiO3 nanoparticles for nitrogen fixation. The ammonia yield of 109.15 μmol g−1 h−1 has been achieved, which is 4.3 times the benchmark for SrTiO3 nanoparticles. This synthesis approach is not inherently limited to material characteristics and can be easily scaled up, which may open up a general route towards high-performance catalysts for commercial applications.
Platinum-based catalysts with heterogeneous structures, such as three-dimensional (3D) nanoframes and highly branched architectures, have broad application prospects due to their fully accessible ...surfaces and high atom utilization. However, the fragile frames and dendrites with high energy easily suffer from structural collapse during catalytic processes. Hence, we synthesized Rh-strengthened PtCuRh rhombohedral dodecahedrons with nanodendrites (RDD) through a one-pot solvothermal method, which could be etched to obtain totally open nanoframe PtCuRh rhombohedral dodecahedrons with nanodendrites (RDND). More interestingly, the growth of the nanodendrites can be easily controlled through changing the reaction temperature. Meanwhile, the length of the nanodendrites can be controlled through adjusting the amount of CTAB and the reaction time. In addition, synergistic effects between Pt, Cu and Rh modified the electronic structure; in particular Rh metal oxide on the surface contributes heavily towards improving the electrocatalytic efficiency. Therefore the as-prepared catalyst PtCuRh RDND shows superior catalytic performance towards the methanol oxidation reaction (MOR) as well as the ethanol oxidation reaction (EOR) compared to TKK-commercial Pt/C. Remarkably, after 1000 electrochemical cycles of the MOR, the superior mass activity of PtCuRh RDND surpasses that of TKK-commercial Pt/C by 2.6 times, benefiting from enhanced CO tolerance and the stable structure. This work provides a facile and feasible strategy for synthesizing stable and efficient nanoframe catalysts.
In this paper, two different Rh-strengthened rhombohedral dodecahedron nanoframes promoting catalytic performance towards the MOR and EOR were synthesized.
Monodisperse alloyed PtCu nanoparticles (NPs) have been synthesized via a facile one-pot hydrothermal method. In addition, this is the first time to obtain self-assembled NPs as a hexagonal array ...with six-fold symmetry in the PtCu NP system. In our synthesis, oleylamine (OAM) is essential for the self-assembly of uniform PtCu NPs. These PtCu spheres have a diameter of 4.78 plus or minus 0.28 nm with a Pt-rich skin and are evaluated as a catalyst for the methanol oxidation reaction. The activity of the PtCu nanoparticles is 34.81 mA cm-2, while that of the PtCu/C catalysts is 24.6 mA cm-2, which is about 6.216 times and 4.4 times higher than that of the Pt/C catalyst (5.6 mA cm-2). Our studies provide a simple approach to synthesize monodisperse PtCu NPs with Pt-rich skin, making it possible to develop highly active catalysts for methanol oxidation.
A novel FeS/Fe3C nanoparticles encapsulated in porous nitrogen-sulfur dual-doped graphene network (FeS/Fe3C@NS-G) have been successfully fabricated via a one-step in-situ pyrolysis strategy. The ...nitrogen and sulfur co-doped graphene networks exhibited abundant mesoporous structure and excellent electrical conductivity, facilitating fast electron transport and lithium-ion diffusion. The heterogeneous FeS/Fe3C nanoparticles are homogeneously dispersed in the three-dimensional porous graphene shell with copious internal void space which can accommodate the volume change of the nanoparticles during electrochemical reaction. The FeS/Fe3C@NS-G nanohybrids delivered excellent reversible capacity of 1003 mAh g−1 after 150 cycles at 0.1 A g−1 with a minor capacity decay rate of 1.25%. Furthermore, an ultralong cycling stability of 610 mAh g−1 after 800 cycles at 1 A g−1 with the capacity retention of 91.6% relative to the reversible capacity of the second cycle was observed. This remarkable lithium storage capacity of FeS/Fe3C@NS-G networks reveals their promising potential as anode materials for lithium-ion batteries.
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•FeS/Fe3C nanoparticles in-situ encapsulated in nitrogen-sulfur dual-doped graphene network (NS-G).•NS-G with the abundant internal void space to accommodate the volume change of FeS/Fe3C nanoparticles during cycling.•The 3D interconnected mesoporous graphene network is formed by the addition of glucose.•FeS/Fe3C@NS-G has high-rate long-term cycling stability as Li-ion battery anode.
In this work, CoNi oxyhydroxide nanosheets CoNi-OOH-30(40) are synthesized, through two simple steps, as efficient bifunctional catalysts in alkaline media. First, a shape-controlled CoNi-X alloy (X ...denotes electrodeposition time) with a ridge-like morphology that in-situ deposited on titanium sheets is obtained by electrodeposition. Then, CoNi-30 with ridge-like structure is further electrooxidized to improve the electrochemical activity. After 40 h oxidation, the CoNi-OOH-30(40) oxyhydroxide with nanosheets structure is obtained, which exhibits good catalytic performance for overall water splitting than the other as-prepared catalysts. It is found that CoNi-OOH-30(40) to reach ±10 mA cm−2 requires small overpotentials of −210 and 279 mV, Tafel slopes of 67 and 62 mV dec˗1 and exhibit good stabilities for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline solution, respectively. A water electrolyzer, using CoNi-OOH-30(40) as anode and cathode catalysts, reaches 10 mA cm−2 at a voltage of 1.76 V. Furthermore, due to the Co‒Ni alloy and CoNi oxyhydroxide, CoNi-OOH-30(40) maintains 10 mA cm−2 for 60 h in alkaline media without activity losses. It is believed that the present work provides a facile, fast and feasible strategy to fabricate cost-efficient CoNi oxyhydroxide nanosheets catalysts with high water splitting efficiency and stability in alkaline conditions.
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•A facile and feasible strategy to fabricate low cost CoNi (oxy)hydroxide catalysts is proposed.•The prepared materials exhibit good water splitting catalytic activity and stability in alkaline media.•An overpotential of −210 mV is required to reach −10 mA cm−2 (HER) and 279 mV to reach +10 mA cm−2 (OER).
