Origin of synergistic effects in bicomponent cobalt oxide-platinum catalysts for selective hydrogenation reaction

Reported herein is comprehensive study of a highly active and stable cobalt catalyst for overall water splitting. This composite SFCNF/Co1−xS@CoN, consisting of S‐doped flexible carbon nanofiber (SFCNF) matrix, Co1−xS nanoparticles, and CoN coatings, is prepared by integration of electrospinning and atomic layer deposition (ALD) technique. Representative results include the following: 1) ultrathin CoN layer is deposited by ALD on the surface of flexible substrate without any sacrifice of SFCNF and Co1−xS; 2) the composite exhibits strong electrocatalytic activity in both acidic and basic solutions. The overpotentials of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are 20 and 180 mV, respectively, at a current density of 10 mA cm−2 in basic medium. A small Tafel slope of 54.4 mV dec−1 is observed in 0.5 m H2SO4 electrolyte; 3) tested as overall water splitting electrode, the composite records a current density of 10 mA cm−2 at a relative low cell voltage of 1.58 V and long‐term stability for 20 h at a current density of up to 50 mA cm−2. The superior performance for overall water splitting is probably attributed to the synergistic effect of Co1−xS and ALD CoN. Specifically, implementation of ALD can be extended to innovate nanostructured materials for overall water splitting and even other renewable energy aspects.

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“…This change is considered to arise from the increase of total mass and volume occupied by surface‐coated ALD CoN thin film. [ 23 ]…”

Section: Resultsmentioning

confidence: 99%

Strategic Atomic Layer Deposition and Electrospinning of Cobalt Sulfide/Nitride Composite as Efficient Bifunctional Electrocatalysts for Overall Water Splitting

Guo

Wang

Zhang

et al. 2020

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“…Ultrathin metal oxides by ALD have been applied to encapsulate the supported nanoparticles and improve the size stability of nanoparticle catalysts 35,36 . In order to minimize additional electrocatalytic effects from ALD overcoating layer, we chose the relatively inert Al 2 O 3 rather than the typical transition metal oxide promotors (e.g., Co 3 O 4 37 , MnO 38 , Fe 2 O 3 39 , and MoO 3 40 ). ALD of a thin Al 2 O 3 layer was carried out to stabilize the ultrasmall PtP 2 NCs on a commercial carbon support by alternately exposing the sample to cycles of trimethylaluminum (TMA) and water at 175°C (Fig.…”

Section: Synthesis and Characterizationmentioning

confidence: 99%

Scalable neutral H2O2 electrosynthesis by platinum diphosphide nanocrystals by regulating oxygen reduction reaction pathways

et al. 2020

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Despite progress in small scale electrocatalytic production of hydrogen peroxide (H 2 O 2) using a rotating ring-disk electrode, further work is needed to develop a non-toxic, selective, and stable O 2-to-H 2 O 2 electrocatalyst for realizing continuous on-site production of neutral hydrogen peroxide. We report ultrasmall and monodisperse colloidal PtP 2 nanocrystals that achieve H 2 O 2 production at near zero-overpotential with near unity H 2 O 2 selectivity at 0.27 V vs. RHE. Density functional theory calculations indicate that P promotes hydrogenation of OOH* to H 2 O 2 by weakening the Pt-OOH* bond and suppressing the dissociative OOH* to O* pathway. Atomic layer deposition of Al 2 O 3 prevents NC aggregation and enables application in a polymer electrolyte membrane fuel cell (PEMFC) with a maximum r(H 2 O 2) of 2.26 mmol h −1 cm −2 and a current efficiency of 78.8% even at a high current density of 150 mA cm −2. Catalyst stability enables an accumulated neutral H 2 O 2 concentration in 600 mL of 3.0 wt% (pH = 6.6).

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“…In general, the hydrogen migration from the metal particles to the support, i.e., hydrogen spillover, is a well-known phenomenon in heterogeneous catalysis and is involved in many important reactions [15][16][17][18][19][20][21][22][23][24] . The efficiency and spatial extent of hydrogen spillover strongly depend on the types of supports 25,26 .…”

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confidence: 99%

In situ tuning of electronic structure of catalysts using controllable hydrogen spillover for enhanced selectivity

et al. 2020

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In situ tuning of the electronic structure of active sites is a long-standing challenge. Herein, we propose a strategy by controlling the hydrogen spillover distance to in situ tune the electronic structure. The strategy is demonstrated to be feasible with the assistance of CoOx/Al2O3/Pt catalysts prepared by atomic layer deposition in which CoOx and Pt nanoparticles are separated by hollow Al2O3 nanotubes. The strength of hydrogen spillover from Pt to CoOx can be precisely tailored by varying the Al2O3 thickness. Using CoOx/Al2O3 catalyzed styrene epoxidation as an example, the CoOx/Al2O3/Pt with 7 nm Al2O3 layer exhibits greatly enhanced selectivity (from 74.3% to 94.8%) when H2 is added. The enhanced selectivity is attributed to the introduction of controllable hydrogen spillover, resulting in the reduction of CoOx during the reaction. Our method is also effective for the epoxidation of styrene derivatives. We anticipate this method is a general strategy for other reactions.

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Origin of synergistic effects in bicomponent cobalt oxide-platinum catalysts for selective hydrogenation reaction

Cited by 149 publications

References 50 publications

Strategic Atomic Layer Deposition and Electrospinning of Cobalt Sulfide/Nitride Composite as Efficient Bifunctional Electrocatalysts for Overall Water Splitting

Strategic Atomic Layer Deposition and Electrospinning of Cobalt Sulfide/Nitride Composite as Efficient Bifunctional Electrocatalysts for Overall Water Splitting

Scalable neutral H2O2 electrosynthesis by platinum diphosphide nanocrystals by regulating oxygen reduction reaction pathways

In situ tuning of electronic structure of catalysts using controllable hydrogen spillover for enhanced selectivity

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