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transparency thus connected networks of 1D nanomaterials [5] have been studied as a viable alternative to thin films of indium tin oxide, which suffer from drawbacks such as brittleness and indium scarcity. [6] Materials such as graphene and transition metal dichalcogenides (TMDs) exhibit excellent electrical properties due to their "flat" 2D chemical structure. Sheets or flakes of these materials can allow for large area coverage with high conductivity but typically at the expense of transparency. [7,8] An approach to improving transparency is utilizing these materials in 1D nanorod-like structures. Carbon nanotubes (CNTs) are the most popular 1D variant of graphene and have been utilized to form large area conducting films, although challenges remain with respect to their purification [9,10] and aggregation. [5] As an alternative to CNTs, the synthesis of carbon-based nanorods has been reported by utilizing arc discharge [11] and microwave plasma chemical vapor deposition (CVD) [12] methods. However, the arc discharge method requires an extensive filtering (Soxhlet extraction) and drying process, while the CVD method requires a high power and temperature (e.g., 850 °C). The growth of graphene nanoribbons has also been reported by ultrahigh vacuum thermal evaporation [13] and hydrothermal techniques, [14] yielding lengths of 20-450 nm and widths of 2-40 nm.In regards to TMDs, molybdenum disulfide (MoS 2 ) nanorods have been synthesized via a redox reaction in an aqueous solution (yielding a nanorod mixture of binary oxides (Mo x O y ) and binary sulfides (Mo x S y )), [15] hydrothermal synthesis, [16] and hydrothermal synthesis of MoO 3 nanorods combined with sulfurization. [17] Similar to MoS 2 , the synthesis of tungsten disulfide (WS 2 ) nanorods has been accomplished by lengthy hydrothermal [18,19] and sulfidation [20] methods. Zhang et al. used high energy ball milling of WS 2 powder for 122 h, after which the powder was used as a precursor in a hydrothermal reaction for nanorod growth. [21] Ball milling methods have also been used to produce boron nitride (BN) nanorods. Boron carbide powders were milled for 100 h and subsequently treated with nitrogen at high temperature to produce BN nanorods. [22][23][24] In another approach, Museur et al. synthesized BN nanorods embedded in amorphous boron suboxides (B x O y ) through UV laser irradiation of a compacted BN powder pellet in a high-pressure nitrogen environment. [25] Table 1 summarizes these previous efforts to fabricate nanorods of 2D materials. Many of these methods require Herein, the previously unrealized ability to grow nanorods and nanotubes of 2D materials using femtosecond laser irradiation is demonstrated. In as short as 20 min, nanorods of tungsten disulfide, molybdenum disulfide, graphene, and boron nitride are grown in solutions. The technique fragments nanoparticles of the 2D materials from bulk flakes and leverages molecular scale alignment by nonresonant intense laser pulses to direct their assembly into nanorods up to several micrometers i...

which is reflected in the sheer number of review articles on the topic. [1-9] Detection of VOCs in exhaled breath has been particularly useful for the diagnosis of a broad range of diseases such as diabetes, liver and lung disorders, and different forms of cancer. [10] 2D nanomaterials such as graphene oxide (GO), molybdenum disulfide (MoS 2), and tungsten disulfide (WS 2) are viable candidates for use in chemical gas sensors due to their large specific surface area that can be tailored for analyte adsorption. 2D nanomaterials have been primarily used for the detection of toxic gasses and pollutants such as nitrogen dioxide (NO 2), hydrogen disulfide (H 2 S), carbon monoxide (CO), and carbon dioxide (CO 2), [1-3,11] while the detection of VOCs by these materials has been limited. GO, [12,13] MoS 2 , [14,15] and WS 2 [16,17] have all shown a response to water vapor or relative humidity changes. Without the aid of other compounds or dopants, graphene oxide has shown a response to ethanol [18,19] and toluene vapors. [20] Similarly, MoS 2 and WS 2 have shown a response to vapors of ethanol, acetone, hexane, toluene, and benzene. [21-23] In most of these reports, the sensing material is casted over a set of interdigitated electrodes to form a chemoresistive sensor. The interaction between analyte vapors and the sensing material (i.e., through

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