Since decades, the PECVD (‘plasma enhanced chemical vapor deposition’) processes have emerged as one of the most convenient and versatile approaches to synthesize either organic or inorganic thin films on many types of substrates, including complex shapes. As a consequence, PECVD is today utilized in many fields of application ranging from microelectronic circuit fabrication to optics/photonics, biotechnology, energy, smart textiles, and many others. Nevertheless, owing to the complexity of the process including numerous gas phase and surface reactions, the fabrication of tailor-made materials for a given application is still a major challenge in the field making it obvious that mastery of the technique can only be achieved through the fundamental understanding of the chemical and physical phenomena involved in the film formation. In this context, the aim of this foundation paper is to share with the readers our perception and understanding of the basic principles behind the formation of PECVD layers considering the co-existence of different reaction pathways that can be tailored by controlling the energy dissipated in the gas phase and/or at the growing surface. We demonstrate that the key parameters controlling the functional properties of the PECVD films are similar whether they are inorganic- or organic-like (plasma polymers) in nature, thus supporting a unified description of the PECVD process. Several concrete examples of the gas phase processes and the film behavior illustrate our vision. To complete the document, we also discuss the present and future trends in the development of the PECVD processes and provide examples of important industrial applications using this powerful and versatile technology.

The engineering of an efficient electrochemical sensor based on a bismuth sulfide/reduced graphene oxide (Bi₂S₃/rGO) composite to detect ascorbic acid (AA) is reported. The Bi₂S₃ nanorods/rGO composite was synthesized using a facile hydrothermal method. By varying the amount of graphene oxide (GO) added to the synthesis, the morphology and size of Bi₂S₃ nanorods anchored on the surface of rGO can be tuned. Compared to a bare glassy carbon electrode (GCE), the GCE modified with Bi₂S₃/rGO composite presented enhanced electrochemical performance, which was attributed to the optimal electron transport between the rGO support and the loaded Bi₂S₃ as well as to an increase in the number of active catalytic sites. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) analysis of Bi₂S₃/rGO/GCE demonstrate that the active Bi₂S₃/rGO layer on GCE plays an important role in the electrochemical behavior of the sensor. In particular, the Bi₂S₃/rGO/GCE sensor shows a wide detecting range (5.0–1200 μM), low detection limit (2.9 µM), good sensitivity (268.8 μA mM⁻¹ cm⁻²), and sufficient recovery values (97.1–101.6%) for the detection of ascorbic acid.