Transformation
of carbon dioxide into various chemicals including
methanol is a top priority field of study owing to the association
of CO2 with global warming. There is a need for renewable
and sustainable energy sources and replacement of fossil fuel with
a fuel having comparable energy density. Electrochemical reduction
is a unique approach to convert CO2 to methanol by employing
alternative energy sources where electrocatalyst plays a crucial role.
A lot of effort is made to understand and increase the efficiency
of electrocatalysts. Unadulterated metals, metal oxide, composite
materials, and metal–organic frameworks (MOFs) are employed
for the electrochemical reduction of CO2 to methanol. However,
MOFs engrossed the enormous consideration due to simplicity, higher
surface area, and unique structural features. In recent years, MOFs
and their derivatives find significant applications in the electrocatalysis
of oxygen and hydrogen evolution, oxygen, hydrogen, and CO2 reduction. The primary emphasis of the current review is the electroreduction
of CO2 to methanol by coalescing the vantages of non-MOFs,
MOFs, and their composite materials. The challenges to achieve electrocatalyst
with higher efficiency and better selectivity for the electroreduction
of CO2 are analyzed. Several research directions are proposed
for MOF electrocatalysts to enhance the catalytic efficiency in methanol
production. This review substantiates the efforts to develop new MOFs
with superior efficiency, chemical stability, and conductivity.
The continuously growing universal
demand for energy and declining
production is fascinating the research community to invent novel technologies.
The oil and gas industry is not only focusing on the discovery of
unexplored reserves but also converging to the irrecoverable hydrocarbon
reserves. For this purpose, a clear understanding of the vital features
of drilling fluid can help to design drilling fluid of selective nature
that can overcome the major issues come across during the oil and
gas drilling operation. The stability of the drilling fluid under
extremely high temperature and high pressure (HTHP) and the environmental
footprint during the oil recovery process are major issues. To get
stable, simpler, and more economical drilling fluids, a wide variety
of nanomaterials have been widely evaluated under varying conditions.
The carbon-based nanomaterials demonstrate the unprecedented physicochemical
features that are considered very crucial for the smart drilling fluid
formulation. The carbon-based nanoparticles (CNPs) are relatively
new in the drilling technology, and they are not implemented up to
their maximum potential. Several researchers have explored CNPs, their
derivatives, and composites to formulate drilling fluid with required
features. The resultant fluid system demonstrates better rheological
features, friction reduction, low environmental impact, and greater
stability under HTHP drilling conditions. However, there are still
challenging aspects that must be addressed to take full advantage
of the capabilities of CNPs. The present work is a comprehensive review
of the recent progress in fluid systems based on carbon nanomaterials,
because of their huge impact on the drilling fluid rheology and environmentally
friendly nature. The nature of carbon-based nanomaterials, size, shape,
and concentration are critically evaluated and discussed in the current
article. Finally, this review paper identifies the opportunities for
future research of the nanocarbon-based drilling fluids and their
applications in the gas and oil exploration sector has been discussed.
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