**1. Introduction**

After discovering graphene in 2004, the two-dimensional (2D) materials have drawn significant attention in broad applications due to their unique physicochemical properties. The 2D materials such as transition metal dichalcogenides (TMDs), phosphorene and bismuthine, etc., which consists of a one-atom-thick monolayer network can exhibit different chemical and physical properties, including the electrical and thermal conductivity, magnetic, photonic and catalytic properties when compared to their bulk counterparts [1]. Over the past few years, the enormous 2D family materials like graphene [2, 3], molybdenum disulphide (MoS2) [4, 5], tungsten disulphide (WS2) [6, 7], graphitic carbon nitride (g-C3N4) [8] and recently MXene [9, 10] have been investigated for various applications in electronic, energy, catalysis and electrochemical applications. However, the electrochemistry investigation of those materials is yet to be explored in detail.

The limitation in the bandgap of these materials has hindered their performance in practical applications. Therefore, exploring a new novel 2D material is highly recommended, especially for the future electrochemical energy conversion, storage, and biosensors applications. Recently, silicon (Si) based one-atom-thick layered material named siloxene has been investigated for electrochemical energy and sensing applications, including supercapacitors, batteries, and dopamine sensors [1, 11–13].

Siloxene is a direct bandgap material that was discovered by Wohler in 1863. It can be obtained through the deintercalation of calcium and exfoliation from the Zintl phase of calcium silicide (CaSi2) powder [14–16]. Different from the graphene planner structure, siloxene possesses a low-buckled structure due to its double band role. As a result of the surface-terminated functional groups with Si chain and the mixed sp2 and sp3 hybridization, siloxene can provide several advantages in the electrochemical energy and sensor applications [1, 11, 12, 17].
