Ketenes are a class of highly reactive organic compounds that play a crucial role as intermediates in organic reactions and industrial organic syntheses [1]. The simplest member of this class is ethenone with the chemical formula of C2H2O. Ethenone is a toxic and sharp odoriferous gas that irritates the nose, eyes, throat, and lungs [2]. Ethenone was discovered through the debromination of bromoacethyl bromide with metallic zinc by Hermann Staudinger in 1908 [3]. Huang et al. found that prolonged standing exposure to a high-concentration mixture of ethenone and crotonaldehyde causes acute respiratory distress syndrome (ARDS) [4]. Attfield et al. suggested that Ethenone which was produced by heating Vitamin E acetate (VEA), contributes to an e-cigarette or vaping use-associate lung injury (EVALY) [5]. Due to the toxicity of Ethenone, it is essential to detect and remove the unwelcome spread of ethenone in the environment. The adsorption of ketenes on various surfaces has been experimentally and theoretically studied [[6], [7], [8], [9], [10]]. White et al. considered the adsorption and dissociation of ketene on Ru(001) surface using high-resolution electron energy loss spectroscopy [7]. They observed that ethenone could be adsorbed on Ru(001) and dissociated to CH2 and CO at 105 K. Also, Hydrogenating ethenone at 200 K caused the production of CH3CHO and CH3CO. In the other work, White et al. studied the photochemistry of ethenone adsorbed on the surface of Pt(111) [8]. Coluccia et al. employed FTIR spectroscopy to investigate the chemisorption of ethenone on the surface of ZnO at room temperature [9]. They observed that ethenone adsorption caused a surface reduction. Bu and Lin showed that ethenone was molecularly adsorbed on the surface of Si(111) at 120 K [6]. Increasing the temperature to 450 K led to ethenone decomposition to CHx and O species.

Porphyrins are a group of aromatic macrocycle organic structures which play an essential role in biological processes such as respiration [11], electron transport [12], and photosynthesis [13]. A porphyrin cycle consists of four functionalized pyrroles connected by methine bridges (=CH-). Porphyrins and porphyrin-based compounds have various applications in medicine, energy, and chemical industries [14]. Because of solid light absorption, Porphyrins have been studied for photodynamic therapy (PDT), a noninvasive cancer treatment [15,16]. Some porphyrin-based compounds have been investigated as anticancer and antioxidant materials [17]. Metalloporphyrins are formed by inserting metal ions into porphyrin cycles. These compounds have been widely studied to use as (photo) catalysts for organic syntheses, organic compound oxidations, and photocatalytic water splitting [18,19]. Also, metalloporphyrin aggregation to TiO2 has been evaluated as suitable dye-sensitized solar cells [20,21]. The application of metalloporphyrins as chemical sensors has attracted much attention [[22], [23], [24], [25], [26]]. For instance, Natale et al. has reviewed the performance of metalloporphyrins for detecting and analyzing volatile compounds [23]. Rakow and Suslick have investigated metalloporphyrins as colorimetric sensors for visualizing odiferous and toxic compounds [24]. The sensor application of metalloporphyrins for rapid detecting trace TNT vapors has been examined by Tao et al. [25]. Amao and Okura have reviewed the application of metalloporphyrins in optical oxygen sensor devices [26]. Lee et al. employed the metalloporphyrin functionalized reduced graphene oxide to analyze human breath and detect volatile organic compounds [27]. Due to unique properties and high effective surface area, carbon nanomaterials have attracted growing researcher's interest to study their various applications, such as gas adsorption, detection, catalyst etc [[28], [29], [30], [31], [32], [33], [34], [35]]. In 2011, Duck Hyun Lee et al. synthesized a Fe-porphyrin-like carbon nanotubes and used them for oxygen reduction as a catalyst [36]. Metalloporphyrin-like graphene was synthesized by Tripkovic et al. and employed for electrochemical CO2 and CO reductions [37]. In 2017, Arshadi and Anisheh theoretically studied the structure and electronic properties of porphyrin-induced C70 fullerene (PIC70F) and Cr+2, Co+2 inserted PIC70F as bulky-ball porphyrin and metalloporphyrins [38]. They showed that Cr+2, Co+2 inserted PIC70Fs have selective sensing behavior toward NO2 gas in the present of SO2 gas. Also, the potential of metalloporphyrin like nanocones for adsorbing and detecting O2 and N2O gases were considered by Arshadi et al. [39,40]. This work tends to study the sensing behavior of Ti+2, Cr+2, Fe+2, Co+2, Ni+2, Cu+2, and Zn+2 inserted PIC70Fs toward ethenone.