###### Abstract  
The use of inhibitors is one of the most efficient methods to protect metals against corrosion, which affects many sectors and generates a significant effect on the world economy. This paper presents a prospection using plant extracts as green corrosion inhibitors, aiming at the use of environmentally friendly input. For this, the authors used scientific articles and patents, with recovery of 335 articles and 42 patents related to the subject, as the source. Most technological solutions consist of extracts prepared from leaves of interest plant species, with tests carried out in acidic corrosive environments, with carbon steel (SAE1020) being the most researched material to be protected. Among the identified technologies, some point to corrosion inhibition greater than 80%. The scientific and patent literature points to the excellent performance of these compounds added to the other data collected in the present study, indicating that the exploration of this area is on the rise and very promising. Special highlight is given to the studies and development of green inhibitors in Brazil, considering the potentialities of its high vegetable biodiversity. corrosion; green inhibitor; plant extracts; patent and bibliographic survey 2023  
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M.P.Q. ; [EMAIL_ADDRESS] (A.S.R. ); [EMAIL_ADDRESS] (T.I) 1  
C.C.C. ; 1  
C.C.C.C. ; 1  
C.C. estimated that in Brazil this expenditure was 4% of GDP. This percentage is equivalent to more than USD 40 billion [5; 6; 7]. The measures commonly used, individually or in combination, to combat corrosion are methods based on process modification (structure design; surface conditions; by the application of cathodic protection), modification of the corrosive environment (deaeration of water or neutral solution; purification or reduction of air humidity; addition of corrosion inhibitors), in the modification of the metal (increase in purity; addition of alloying elements; heat treatment) and in protective coatings (coatings with reaction products, such as chemical or electrochemical treatment of the metal surface; organic coatings, such as paints, resins or polymers; inorganic coatings, such as enamels and cements; metallic coatings; temporary protectors) [2]. One of the most practical methods to protect metal materials is the use of corrosion inhibitors. They are a class of substances capable of slowing the corrosion of a metal when added in low concentration to the environment to which it will be exposed. Its mechanism of action is associated with the formation of a protective barrier adsorbed on its surface, which interacts with the reaction sites and decreases the oxidation and/or reduction reactions associated with corrosion [8; 9; 10], thus, the inhibitors protect metals by slowing down the corrosion processes in one of the following ways: (1) increasing the anodic or cathodic polarization behavior (Tafel curves); (2) reducing the movement or diffusion of ions to the metallic surface and (3) increasing the electrical resistance of the metallic surface [9]. They are commonly classified by their action as cathodic, anodic and mixed inhibitors [10]. The cathodic inhibitors, also known as precipitation inhibitors, work by suppressing cathodic reactions. In this way, the reaction in the cathode is delayed or prevented, limiting the diffusion of the reducing species to the surface. These inhibitors present, in their composition, metallic ions capable of producing a cathodic reaction due to alkalinity, producing insoluble compounds that selectively precipitate in cathodic regions, increasing the protection of the surface from the diffusion process of reducing species, that is, the diffusion of oxygen and electrons drivers in these regions. The anodic inhibitors, also called passivation inhibitors, are those that act by suppressing anodic reactions. In this way, the reaction at the anode is retarded or impeded, due to the formation of an insoluble film adsorbed on the metal.