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Dang et al. Chem Synth 2023;3:14 https://dx.doi.org/10.20517/cs.2022.33 Page 15 of 20

Figure 7. (A) (i) and (ii) Schematic illustration of the synthesis process of the Se@PCNFs electrode; (iii) Photograph of free-standing
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and flexible Se@PCNFs electrode; (iv) Long-term cycling performance of Se@PCNFs electrode in Li-ion batteries at 0.5 A g for 900
cycles [103] ; Copyright 2015, Wiley-VCH. (B) (i) Digital photo of the flexible self-standing graphene-Se@CNT composite film;
(ii) Charge/discharge profiles of the graphene-Se@CNT composite film with cycles at 0.1 C current rate; (iii) Cycling performance of
the self-standing graphene-Se@CNT at 0.1 C [104] ; Copyright 2014, Elsevier. (C) (i) Schematic illustration of the synthesis process for
Se@MCNF electrode; (ii) photograph of flexible and freestanding Se@MCNF electrode; (iii) Cyclic performances of the Se@MCNF
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electrode at a current density of 0.1 A g and coulombic efficiency during cycling [105] ; Copyright 2017, Wiley-VCH.

Synthesis and fabrication: The fabrication of high-performance Se nanomaterial-based flexible and
wearable electronic devices relies on the precise positioning and alignment of Se nanomaterials. Most
existing approaches to Se nanomaterials synthesis are built upon solution-based processes that involve
complex chemical reactions, producing Se nanomaterials with irregular positioning and agglomeration or
entanglement. The fabrication of well-ordered, highly uniform Se nanomaterials remains a significant
challenge. Moreover, the solution-based approaches, for the most part, exploit noxious raw materials such
as Na SeO and H SeO . Their inappropriate handling poses a significant threat to the environment. While
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solution-free methods such as PVD and CVT only process bulky Se, fulfilling the requirements of high
temperature, high-vacuum environment, and highly purified gases demands high operation costs, which
undermines the possibility of large-scale production. More controllable, effective, and eco-friendly synthesis
and fabrication methods are heavily needed. The recent innovation in harnessing the multimaterial thermal
drawing platform has demonstrated a unique and powerful platform for manufacturing periodic arrays of
Se nanomaterials in an unprecedentedly green, sustainable and scalable manner [70,76,106-108] . The research along
this direction has just begun and is expected to be an exciting paradigm for next-generation Se
nanomaterial-based flexible and wearable electronics.