555 ISSN 1063-7850, Technical Physics Letters, 2016, Vol. 42, No. 6, pp. 555–558. © Pleiades Publishing, Ltd., 2016. Original Russian Text © V.Yu. Fominski, S.N. Grigoriev, R.I. Romanov, M.A. Volosova, A.I. Grunin, G.D. Teterina, 2016, published in Pis’ma v Zhurnal Tekhnicheskoi Fiziki, 2016, Vol. 42, No. 11, pp. 1–9. The Formation of a Hybrid Structure from Tungsten Selenide and Oxide Plates for a Hydrogen-Evolution Electrocatalyst V. Yu. Fominski a *, S. N. Grigoriev b , R. I. Romanov a , M. A. Volosova b , A. I. Grunin c , and G. D. Teterina a a National Research Nuclear University MEPhI , Moscow, 115409 Russia b Moscow State University of Technology “STANKIN,” Moscow, 127055 Russia c Immanuel Kant Baltic Federal University, Kaliningrad, 236041 Russia *e-mail: vyfominskij@mephi.ru Received January 6, 2016 Abstract—It has been found that the pulsed laser deposition of a thin tungsten selenide film, followed by ther- mal treatment at 550°C in an Ar + O 2 mixture of gases, results in the formation of a hybrid structure that is made up of ultrathin WSe 2 and WO 3 – y platelets. The structural and size characteristics of the nanoplatelets deposited on microcrystalline graphite provide the effective hydrogen evolution reaction in a 0.5 M H 2 SO 4 solution, with the cathode current made about seven times higher at a potential of –100 mV and the slope of the Tafel characteristic reduced from 340 to 90 mV/dec. DOI: 10.1134/S1063785016060055 At present, 2D and quasi-2D (Q2D, constituted by several molecular layers) structures from the group of transition metal dichalcogenides (TMDs) and, in par- ticular, tungsten diselenide WSe 2 are attracting much attention from researchers because of their recently found very good catalytic properties for activating the electrochemical reaction in which hydrogen is evolved in a solution of acids [1]. The comparatively low price of TMDs makes it possible to consider these materials as a real alternative to the currently used catalysts com- posed of platinum-group metals. The main work of researchers in solving the problem of obtaining effec- tive and inexpensive electrocatalysts are focused on improving the structure and morphology of 2D/Q2D films based on TMD materials and on developing highly efficient and ecologically clean processes for their synthesis. It is commonly believed that the high catalytic activity of nanostructured TMD materials is due to the specific features of the atomic packing of atoms at edges of basal planes (molecular layers/sheets) from which ultrathin catalyst platelets are composed. The extent to which the catalytic activity of films based on TMD materials can be raised is limited both by the difficultly controllable agglomeration of the nano- platelets, which diminishes the surface density of cat- alytically active sites, and by the low conductivity of the TMD materials themselves, including high con- tact resistance at the place of attachment of the nano- platelets to the substrate [2, 3]. Certain opportunities to overcome these limita- tions are opened up when hybrid catalysts are formed that are constituted by nanoplatelets of a TMD mate- rial and ultrathin layers of a chemically stable material with high conductivity. In [3, 4], a hybrid of MoSe 2 nanoplatelets and graphene was obtained that pos- sessed improved catalytic properties as compared with purely MoSe 2 nanoplatelets. The hybrid structure is, for the most part, fabricated by chemical deposition from a vapor or liquid phase. The problem of how the nature of an additive component affects the properties of a catalyst having a hybrid structure is of particular scientific and practical importance. It also seems important to solve the problem of developing ecologi- cally safer physical methods to obtain hybrid TMD- containing catalysts with improved characteristics. The goal of our study was to develop a procedure for fabrication of a thin-film hybrid material contain- ing ultrathin WSe 2 and WO 3 – y plates and to study its catalytic properties. Transition metal oxides also have a layered packing of atoms in the crystal lattice and strongly change their physicochemical properties when the crystal becomes smaller, i.e., when ultrathin 2D/Q2D layers are formed. In contrast to “bulk” WO 3 samples, nanostructured oxides may have a good con- ductivity and improved catalytic properties in the reaction of hydrogen evolution in an acid solution [5, 6]. WO 3 is also characterized by a substantial decrease in resistance in the interaction with hydrogen [7].