Despite of the numerous efforts [90 92], acquiring air-stable and reproducible n-type carbon nanotube transistors in a facile way remains challenging.
It has remained a challenge to develop a facile and scalable approach to synthesize high-energy lithium-ion battery (LIB) electrode materials with excellent rate capabilities and prominent cycling stabilities for their applications in new generation energy storage devices.
Therefore, it is still a challenge to develop a facile, green, and cost-effective method to fabricate multifunctional nanomaterials.
It is still a challenge to explore a facile approach for fabricating porous Sn-based oxide anode materials with controllable morphology and good electrochemical properties for practical applications.
Therefore, it still remains an enormous challenge to develop a facile room-temperature method that needs not any seed layer or metal catalyst for producing hierarchical ZnO structures.
Therefore, it is highly desirable and significant, as well as a big challenge, to develop a facile route to directly synthesize the relatively straight and uniformly dispersed nanotubes of Sb.
However, scalable preparation of Ti3C2 MXene-based composites, especially, integrated with one-dimensional (1D) materials through a facile low-temperature strategy remains a considerable challenge.
To obtain well-designed and well-constructed ZnO micro/nano-architecture via a facile and inexpensive procedure is still a major challenge.
Therefore, the controlling growth of aligned CdS nanotubes and getting ordered nanostructures on conductive substrates by a facile and versatile synthetic method is still a challenge.
It was still a challenge to directly acquire porous/mesoporous hematite nanoarchitectures via a facile, environmentally benign, and low-cost route.
The principal hero of this struggle was Emerson, whose reputation Mr. Poirier did much to redefine, challenging the familiar view of him as a facile optimist, a woozy metaphysician or an enabler of laissez-faire capitalism.
