Ru has recently been considered as a promising alternative of Pt toward hydrogen oxidation reaction (HOR) due to its lower price and similar hydrogen binding energy (HBE) in comparison to Pt. ...Nevertheless, the catalytic performance of Ru toward HOR is far from the satisfaction of practical application. Herein, it is demonstrated that the modification of Ru multi‐layered nanosheet (MLNS) with Ni can significantly promote the HOR performance. In particular, the HOR performance is strongly related to the Ni location on the surface or in the lattice of Ru MLNS. Experimental and theoretical investigations suggest that Ni in the lattice of Ru MLNS (lattice engineering) optimizes the HBE, while Ni species on the surface (surface engineering) decrease the free energy of water formation, as a result of the significantly enhanced HOR performance. The optimal catalyst, where Ni is located both on the surface and in the lattice, displays superior alkaline HOR performance to commercial Pt/C and Ru/C. The present study not only systematically reveals the significance of Ni modification on Ru toward HOR, but also promotes the fundamental researches on catalyst design for fuel cell reactions and beyond.
Herein, it is demonstrated that the lattice and surface engineering of Ru multi‐layered nanosheet with Ni can optimize the hydrogen binding energy and facilitate the adsorption of *OH and the formation of water, as a result of the significant enhancement on alkaline hydrogen oxidation reaction performance.
High‐entropy alloys (HEAs) have been attracting extensive research interests in designing advanced nanomaterials, while their precise control is still in the infancy stage. Herein, we have reported a ...well‐defined PtBiPbNiCo hexagonal nanoplates (HEA HPs) as high‐performance electrocatalysts. Structure analysis decodes that the HEA HP is constructed with PtBiPb medium‐entropy core and PtBiNiCo high‐entropy shell. Significantly, the HEA HPs can reach the specific and mass activities of 27.2 mA cm−2 and 7.1 A mgPt−1 for formic acid oxidation reaction (FAOR), being the record catalyst ever achieved in Pt‐based catalysts, and can realize the membrane electrode assembly (MEA) power density (321.2 mW cm−2) in fuel cell. Further experimental and theoretical analyses collectively evidence that the hexagonal intermetallic core/atomic layer shell structure and multi‐element synergy greatly promote the direct dehydrogenation pathway of formic acid molecule and suppress the formation of CO*.
High‐entropy alloy hexagonal nanoplates (HEA HP) with PtBiPb medium‐entropy core and PtBiNiCo high‐entropy shell has been successfully achieved. The HEA HP not only displays the record formic acid oxidation reaction (FAOR) performance, but also readily achieves much higher peak power density (321.2 mW cm−2) along with the long‐term lifetime under the operating fuel cell conditions.
Abstract
Ion leaching from pure-phase oxygen-evolving electrocatalysts generally exists, leading to the collapse and loss of catalyst crystalline matrix. Here, different from previous design ...methodologies of pure-phase perovskites, we introduce soluble BaCl
2
and SrCl
2
into perovskites through a self-assembly process aimed at simultaneously tuning dual cation/anion leaching effects and optimizing ion match in perovskites to protect the crystalline matrix. As a proof-of-concept, self-assembled hybrid Ba
0.35
Sr
0.65
Co
0.8
Fe
0.2
O
3-
δ
(BSCF) nanocomposite (with BaCl
2
and SrCl
2
) exhibits the low overpotential of 260 mV at 10 mA cm
-2
in 0.1 M KOH. Multiple
operando
spectroscopic techniques reveal that the pre-leaching of soluble compounds lowers the difference of interfacial ion concentrations and thus endows the host phase in hybrid BSCF with abundant time and space to form stable edge/face-sharing surface structures. These self-optimized crystalline structures show stable lattice oxygen active sites and short reaction pathways between Co–Co/Fe metal active sites to trigger favorable adsorption of OH
−
species.
The development of high‐performance catalysts with high activity, selectivity, and stability are essential for the practical applications of H2O2 electrosynthesis technology, but it is still ...formidably challenging. It is reported that the low‐coordinated structure of Pd sites in amorphous PdSe2 nanoparticles (a‐PdSe2 NPs) can significantly boost the electrocatalytic synthesis of H2O2. Detailed investigations and theoretical calculations reveal that the disordered arrangement of Pd atoms in a‐PdSe2 NPs can promote the activity, while the Pd sites with low‐coordinated environment can optimize the adsorption toward oxygenated intermediate and suppress the cleavage of O–O bond, leading to a significant enhancement in both the H2O2 selectivity and productivity. Impressively, a‐PdSe2 NPs/C exhibits high H2O2 selectivity over 90% in different pH electrolytes. H2O2 productivities with ≈3245.7, 1725.5, and 2242.1 mmol gPd−1 h−1 in 0.1 m KOH, 0.1 m HClO4, and 0.1 m Na2SO4 can be achieved, respectively, in an H‐cell electrolyzer, being a pH‐universal catalyst for H2O2 electrochemical synthesis. Furthermore, the produced H2O2 can reach 1081.8 ppm in a three‐phase flow cell reactor after 2 h enrichment in 0.1 m Na2SO4, showing the great potential of a‐PdSe2 NPs/C for practical H2O2 electrosynthesis.
Amorphous PdSe2 nanoparticles (a‐PdSe2 NPs) with low‐coordinated Pd sites have been successfully prepared and applied as highly efficient catalysts for H2O2 electrosynthesis. The low‐coordinated Pd sites with disordered arrangement in a‐PdSe2 NPs canoptimize the adsorption toward oxygenated intermediate and suppress the cleavage of O–O bond, leading to significant enhancement on the catalytic performance toward H2O2 electrosynthesis.
Heterojunction nanostructures usually exhibit enhanced properties in compariosn with their building blocks and are promising catalyst candidates due to their combined surface and unique interface. ...Here, for the first time we realized the oriented growth of ultrasmall metal nanoparticles (NPs) on metal–organic framework nanosheets (MOF NSs) by precisely regulating the reduction kinetics of metal ions with solvents. In particular, a rapid reduction of metal ions leads to the random distribution of metal NPs on the surface of MOF NSs, while a slow reduction of metal ions results in the oriented growth of NPs on the edge of MOF NSs. Impressively, the strong synergy between Pt NPs and MOF NSs significantly enhances the hydrogen evolution reaction (HER) performance, and the optimal catalyst displays HER activities superior to those of a composite with a random growth of Pt NPs and commercial Pt/C under both acidic and alkaline conditions. Moreover, the versatility of such oriented growth has been extended to other metal NPs, such as Pd, Ag, and Au. We believe this work will promote research interest in material design for many potential applications.
Abstract
Electrochemical CO
2
reduction (ECR) is highly attractive to curb global warming. The knowledge on the evolution of catalysts and identification of active sites during the reaction is ...important, but still limited. Here, we report an efficient catalyst (Ag-D) with suitable defect concentration operando formed during ECR within several minutes. Utilizing the powerful fast operando X-ray absorption spectroscopy, the evolving electronic and crystal structures are unraveled under ECR condition. The catalyst exhibits a ~100% faradaic efficiency and negligible performance degradation over a 120-hour test at a moderate overpotential of 0.7 V in an H-cell reactor and a current density of ~180 mA cm
−2
at −1.0 V vs. reversible hydrogen electrode in a flow-cell reactor. Density functional theory calculations indicate that the adsorption of intermediate COOH could be enhanced and the free energy of the reaction pathways could be optimized by an appropriate defect concentration, rationalizing the experimental observation.
Abstract
Herein, we present a scalable approach for the synthesis of a hydrogen-bonded organic–inorganic framework via coordination-driven supramolecular chemistry, for efficient remediation of trace ...heavy metal ions from water. In particular, using copper as our model ion of interest and inspired by nature’s use of histidine residues within the active sites of various copper binding proteins, we design a framework featuring pendant imidazole rings and copper-chelating salicylaldoxime, known as zinc imidazole salicylaldoxime supramolecule. This material is water-stable and exhibits unprecedented adsorption kinetics, up to 50 times faster than state-of-the-art materials for selective copper ion capture from water. Furthermore, selective copper removal is achieved using this material in a pH range that was proven ineffective with previously reported metal–organic frameworks. Molecular dynamics simulations show that this supramolecule can reversibly breathe water through lattice expansion and contraction, and that water is initially transported into the lattice through hopping between hydrogen-bond sites.
Electrochemical two‐electron oxygen reduction reaction (2 e− ORR) to produce hydrogen peroxide (H2O2) is a promising alternative to the energetically intensive anthraquinone process. However, there ...remain challenges in designing 2 e− ORR catalysts that meet the application criteria. Here, we successfully adopt a microwave‐assisted mechanochemical‐thermal approach to synthesize hexagonal phase SnO2 (h‐SnO2) nanoribbons with largely exposed edge structures. In 0.1 M Na2SO4 electrolyte, the h‐SnO2 catalysts achieve the excellent H2O2 selectivity of 99.99 %. Moreover, when employed as the catalyst in flow cell devices, they exhibit a high yield of 3885.26 mmol g−1 h−1. The enhanced catalytic performance is attributed to the special crystal structure and morphology, resulting in abundantly exposed edge active sites to convert O2 to H2O2, which is confirmed by density functional theory calculations.
A new hexagonal phase SnO2 nanoribbon with abundant edge‐active sites has been successfully synthesized by microwave‐assisted mechanochemical‐thermal method. Due to its special structure and morphology, the h‐SnO2 catalysts exhibit near 100 % H2O2 selectivity.
Hybrid metal nanoparticles can allow separate reaction steps to occur in close proximity at different metal sites and accelerate catalysis. We synthesized iron-nickel hydroxide–platinum (transition ...metal-OH-Pt) nanoparticles with diameters below 5 nanometers and showed that they are highly efficient for carbon monoxide (CO) oxidation catalysis at room temperature. We characterized the composition and structure of the transition metal–OH-Pt interface and showed that Ni2+ plays a key role in stabilizing the interface against dehydration. Density functional theory and isotope-labeling experiments revealed that the OH groups at the Fe3+-OH-Pt interfaces readily react with CO adsorbed nearby to directly yield carbon dioxide (CO2) and simultaneously produce coordinatively unsaturated Fe sites for O2 activation. The oxide-supported PtFeNi nanocatalyst rapidly and fully removed CO from humid air without decay in activity for 1 month.
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