2 research outputs found
Electrochemical and SECM Investigation of MoS<sub>2</sub>/GO and MoS<sub>2</sub>/rGO Nanocomposite Materials for HER Electrocatalysis
Development
of advanced materials for electrocatalytic and photocatalytic
water splitting is the key in utilization of renewable energy. In
the present work, we have synthesized MoS<sub>2</sub> nanoparticles
embedded over the graphene oxide (GO) and reduced graphene oxide (rGO)
layer for superior catalytic activity in the hydrogen evolution process
(HER). The nanocomposite materials are characterized using different
spectroscopic and microscopic measurements. A Tafel slope of ∼40
mV/decade suggested the Volmer–Heyrovsky mechanism for the
HER process with MoS<sub>2</sub>/GO composite as the catalyst, which indicated that electrochemical
desorption of hydrogen is the rate-limiting step. The small Tafel
slope indicates a promising electrocatalyst for HER in practical application.
MoS<sub>2</sub>/GO composite material has shown superior catalytic
behavior compared to that of MoS<sub>2</sub>/rGO composite material.
The HER catalytic activity of the catalysts is explored using scanning
electrochemical microscopy (SECM) using the feedback and redox competition
mode in SECM. The activation energy for HER activity was calculated,
and the values are in the range of 17–6 kJ/mol. The lower value
of activation energy suggested faster HER kinetics
Freeze-Casting of Multifunctional Cellular 3D-Graphene/Ag Nanocomposites: Synergistically Affect Supercapacitor, Catalytic, and Antibacterial Properties
Developments of new
and highly effective multifunctional materials
have been shown great interest in recent years. Herein, we report
a simple, cost efficient, one-step, surfactant-free cellular 3D-graphene/Ag
nanocomposite using the freeze-casting method and explore it further
for supercapacitor, catalytic, and antibacterial applications. FE-SEM
and HRTEM analyses of nanocomposites revealed a 3D-cellular network
structure having continuous micrometer size open pores with uniformly
decorated Ag nanoparticles of an average size of 25 nm. An electrochemical
study exhibited the highest specific capacitance at 845 Fg<sup>–1</sup> at 5 mV s<sup>–1</sup> and excellent cyclic retention ∼97%
even after 1000 cycles. Further, 3D-graphene/Ag nanocomposites are
applied as catalyst to reduce methylene blue using NaBH<sub>4</sub>. A rate of reduction above 99% was attained for 3D-graphene/Ag (40%)
nanocomposites, which is significantly higher than that of pristine
3D-graphene. The network like structure of the 3D-graphene/Ag nanocomposite
filtered out 37% of the population from total bacterial strains. Also,
the 3D-graphene/Ag nanocomposite killed almost 100% of the bacterial
strains after 3 h of incubation due to a merging effect of Ag ions
and 3D-graphene