Molybdenum Disulfide Nanosheets Decorated with Platinum Nanoparticle as a High Active Electrocatalyst in Hydrogen Evolution Reaction

Electrochemical hydrogen evolution reaction (HER) refers to the process of generating hydrogen by splitting water molecules with applied external voltage on the active catalysts. HER reaction in the acidic medium can be studied by different mechanisms such as Volmer reaction (adsorption), Heyrovsky reaction (electrochemical desorption) or Tafel reaction (recombination). In this paper, facile hydrothermal methods are utilized to synthesis a high-performance metal-inorganic composite electrocatalyst, consisting of platinum nanoparticles (Pt) and molybdenum disulfide nanosheets (MoS2) with different platinum loading. The as-synthesized composite is further used as an electrocatalyst for HER. The as-synthesized Pt/Mo-90-modified glassy carbon electrode shows the best electrocatalytic performance than pure MoS2 nanosheets. It exhibits Pt-like performance with the lowest Tafel slope of 41 mV dec−1 and superior electrocatalytic stability in an acidic medium. According to this, the HER mechanism is related to the Volmer-Heyrovsky mechanism, where hydrogen adsorption and desorption occur in the two-step process. According to electrochemical impedance spectroscopy analysis, the presence of Pt nanoparticles enhanced the HER performance of the MoS2 nanosheets because of the increased number of charge carriers transport.

The Role of the Double Layer for the Pseudocapacitance of the Hydrogen Adsorption on Platinum

Pseudocapacitances such as the hydrogen adsorption on platinum (HAoPt) are associated with faradaic chemical processes that appear as capacitive in their potentiodynamic response, which was reported to result from the kinetics of adsorption processes. This study discusses an alternative interpretation of the partly capacitive response of the HAoPt that is based on the proton transport of ad- or desorbed hydrogen in the double layer. Potentiodynamic perturbations of equilibrated surface states of the HAoPt lead to typical double layer responses with the characteristic resistive-capacitive relaxations that overshadow the fast adsorption kinetics. A potential-dependent double layer representation by a dynamic transmission line model incorporates the HAoPt in terms of capacitive contributions and can computationally reconstruct the charge exchanged in full range cyclic voltammetry data. The coupling of charge transfer with double layer dynamics displays a novel physicochemical theory to explain the phenomenon of pseudocapacitance and the mechanisms in thereon based supercapacitors.

Construction of efficient bismuth/boron-based flexible electrode in organic media toward neutral hydrogen evolution

Preparing high-efficient, low-cost and stable catalysts to produce hydrogen in neutral electrolyte is a major challenge due to the sluggish kinetics, low conductivity and complex hydrogen adsorption-desorption process. Here, series...

Co Loading Adjustment for the Effective Obtention of a Sedative Drug Precursor through Efficient Continuous-Flow Chemoselective Hydrogenation of 2-Methyl-2-pentenal

This work presents the effect of Co loading on the performance of CNR115 carbon-supported catalysts in the continuous-flow chemoselective hydrogenation of 2-methyl-2-pentenal for the obtention of 2-methylpentanal, an intermediate in the synthesis of the sedative drug meprobamate. The Co loading catalysts (2, 6, 10, and 14 wt.%) were characterized by Brunauer–Emmett–Teller (BET) surface area analysis, transmission electron microscopy (TEM), H2 temperature-programmed reduction (H2-TPR), temperature-programmed desorption of hydrogen (H2-TPD) analysis, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy for selected samples, and have been studied as hydrogenation catalysts at different pressure and temperature ranges. The results reveal that a certain amount of Co is necessary to achieve significant conversion values. However, excessive loading affects the morphological parameters, such as the surface area available for hydrogen adsorption and the particle size, preventing an increase in conversion, despite the increased presence of Co. Moreover, the larger particle size, caused by increasing the loading, alters the chemoselectivity, favouring the formation of 2-methyl-2-pentenol and, thus, decreasing the selectivity towards the desired product. The 6 wt.% Co-loaded material demonstrates the best catalytic performance, which is related to the formation of NPs with optimum size. Almost 100% selectivity towards 2-methylpentanal was obtained for the catalysts with lower Co loading (2 and 6 wt.%).

A Review on Advanced Manufacturing for Hydrogen Storage Applications

Hydrogen is a notoriously difficult substance to store yet has endless energy applications. Thus, the study of long-term hydrogen storage, and high-pressure bulk hydrogen storage have been the subject of much research in the last several years. To create a research path forward, it is important to know what research has already been done, and what is already known about hydrogen storage. In this review, several approaches to hydrogen storage are addressed, including high-pressure storage, cryogenic liquid hydrogen storage, and metal hydride absorption. Challenges and advantages are offered based on reported research findings. Since the project looks closely at advanced manufacturing, techniques for the same are outlined as well. There are seven main categories into which most rapid prototyping styles fall. Each is briefly explained and illustrated as well as some generally accepted advantages and drawbacks to each style. An overview of hydrogen adsorption on metal hydrides, carbon fibers, and carbon nanotubes are presented. The hydrogen storage capacities of these materials are discussed as well as the differing conditions in which the adsorption was performed under. Concepts regarding storage shape and materials accompanied by smaller-scale advanced manufacturing options for hydrogen storage are also presented.