Water
splitting via an electrochemical process
to generate hydrogen is an economic and green approach to resolve
the looming energy and environmental crisis. The rational design of
multicomponent materials with seamless interfaces having robust stability,
facile scalability, and low-cost electrocatalysts is a grand challenge
to produce hydrogen by water electrolysis. Herein, we report a superhydrophilic
homogeneous bimetallic phosphide of Ni2P–CuP2 on Ni-foam-graphene-carbon nanotubes (CNTs) heterostructure
using facile electrochemical metallization followed by phosphorization
without any intervention of metal-oxides/hydroxides. This bimetallic
phosphide shows ultralow overpotentials of 12 (HER, hydrogen evolution
reaction) and 140 mV (OER, oxygen evolution reaction) at current densities
of 10 and 20 mA/cm2 in acidic and alkaline mediums, respectively.
The excellent stability lasts for at least for 10 days at a high current
density of 500 mA/cm2 without much deviation, inferring
the practical utilization of the catalyst toward green fuel production.
Undoubtedly, the catalyst is capable enough for overall water splitting
at a very low cell voltage of 1.45 V @10 mA/cm2 with an
impressive stability of at least 40 h, showing a minimum loss of potential.
Theoretical study has been performed to understand the reaction kinetics
and d-band shifting among metal atoms in the heterostructure (Ni2P–CuP2) that favor the HER and OER activities,
respectively. In addition, the catalyst demonstrates an alternate
transformation of solar energy to green H2 production using
a standard silicon solar cell. This work unveils a smart design and
synthesizes a highly stable electrocatalyst against an attractive
paradigm of commercial water electrolysis for renewable electrochemical
energy conversion.
This
work demonstrates the chiral-induced spin selectivity effect for inorganic
copper oxide films and exploits it to enhance the chemical selectivity
in electrocatalytic water splitting. Chiral CuO films are electrodeposited
on a polycrystalline Au substrate, and their spin filtering effect
on electrons is demonstrated using Mott polarimetry analysis of photoelectrons.
CuO is known to act as an electrocatalyst for the oxygen evolution
reaction; however, it also generates side products such as H2O2. We show that chiral CuO is selective for O2; H2O2 generation is strongly suppressed on
chiral CuO but is present with achiral CuO. The selectivity is rationalized
in terms of the electron spin-filtering properties of the chiral CuO
and the spin constraints for the generation of triplet oxygen. These
findings represent an important step toward the development of all-inorganic
chiral materials for electron spin filtering and the creation of efficient,
spin-selective (photo)electrocatalysts for water splitting.
We report a facile
design and synthesis of magnetic iron oxide
(IO) incorporated chitosan-graphene oxide (CSGO) hydrogel nanocomposites
(CSGOIO) by employing in situ mineralization of iron
ions in a hydrogel matrix. The mechanism of their formation was investigated
by various physical methods, viz., FTIR, XRD, VSM, TGA, SEM, TEM,
and BET. This approach was shown to have a direct impact on the morphological
features and the structural order of the nanocomposites. The potential
of the prepared nanocomposites for effective removal of a cationic
dye, methylene blue (MB), from aqueous solution was investigated by
performing a series of batch adsorption experiments, in line with
the effect of adsorbent dosage, initial dye concentration, contact
time, pH, ionic strength, and temperature. The adsorption was fairly
influenced by the pH and ionic strength of the medium, indicating
an electrostatic interaction between the adsorbent and MB molecules.
The kinetics of adsorption followed a pseudo-second-order model, and
equilibrium capacity was described by the Freundlich adsorption model.
Interestingly, the nanocomposites exhibited a fast removal performance
with a rate constant of 0.06 g mg–1 min–1. The hydrogel nanocomposites were found to possess an excellent
adsorptive property after four successive cycles at different pH of
the solution, thus providing a cost-effective material for dye removal
applications. Therefore, this material, enabling dye removal in a
wide variety of solution conditions, offered a promising platform
for sustainable development of water purification technology.
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