(Bi)metal sulfide polymer composite material, and its use as catalyst for hydrogen production

#The present invention relates to a composite polymer material made of a sulfur-containing polymer able to bind metal sites through sulfur atoms (or sulfur-based ligating sites) and amorphous (bi)metal sulfide nanoparticles. The invention also relates to a method of preparation of a composite material according to the invention. The use of a composite material according to the invention as a catalyst for hydrogen production is also part of the invention. Finally, the invention concerns a proton-exchange membrane (PEM) electrolyser and a photoelectrochemical cell, both comprising a composite material according to the invention.

#The project leading to the present patent application has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No 836429).

#Metal sulfides such as molybdenum sulfides are very attractive noble-metal-free electrocatalysts for the hydrogen evolution reaction (HER) from water. For example, HER-active for amorphous molybdenum sulfide (a-MoSx), prepared either as nanoparticles or as films, is a molecular-based coordination polymer consisting of discrete [Mo3S7]4+ clusters, hereafter named [Mo]3 clusters, linked by disulfide (S22−) anions to other clusters. Such a molecular structure explains some of the special properties of a-MoSx, such as its catalytic activity, reductive activation and corrosion. In some clusters, disulfide (S22−), oxo (O2−) or sulfido (S2−) ligands remain unshared and are designed as terminal ligands. Under reductive aqueous conditions, these terminal ligands are displaced which allows molybdenum hydride moieties to form as the active site for H2 evolution. These HER electrocatalysts are therefore of considerable interest as far as they appear as an alternative to platinum. Indeed, Pt-based catalysts suffer of being both scarce and expensive despite their high performance and stability.

#FIG. 1 illustrates the composite structure of a catalyst according to the invention showing amorphous molybdenum sulfide (a-MoSx) based on [Mo]3 clusters stabilized by a sulfur-based coordinating functions.

#FIG. 2 shows the polarization curves for HER obtained with amorphous a-MoSx catalyst (two different batches) (representative of the prior art) and with the composite a-MoSx-P3HT material (catalyst of the invention), wherein the surface used is the geometric surface of the electrode.

#FIG. 3 shows the polarization curves for HER obtained with the composite a-MoSx-P3HT material (catalyst of the invention) (washed and unwashed), wherein the surface used is the geometric surface of the electrode.

#The present invention relates to a composite material made of: amorphous (bi)metal sulfide nanoparticles based on amorphous (bi)metal sulfide clusters, directly linked, through coordinate covalent bonds, to a sulfur-containing polymer.

#In the sense of the invention, amorphous (bi)metal sulfide nanoparticles encompasses amorphous single-metal sulfide nanoparticles and amorphous bi-metal sulfide nanoparticles. Therefore, according to a first embodiment, the amorphous (bi)metal sulfide nanoparticles are amorphous single-metal sulfide nanoparticles. According to a second embodiment, the amorphous (bi)metal sulfide nanoparticles amorphous bi-metal sulfide nanoparticles, wherein the metals of the amorphous bi-metal sulfide are different.

#The metal(s) of the amorphous (bi)metal sulfide nanoparticles of the invention may be advantageously chosen in the group consisting of metal of the columns 5 and 6 of the periodic table (table of Mendeleiev), optionally combined (when the amorphous (bi)metal sulfide is an amorphous bi-metal sulfide) with another element chosen in the group consisting of the columns 4 to 11 of the periodic table. In a preferred embodiment, the metal(s) of the amorphous (bi)metal sulfide nanoparticles of the invention is chosen in the group consisting of Mo, V, and W, optionally in combination with (when the amorphous (bi)metal sulfide is an amorphous bi-metal sulfide) another element preferably chosen in the group consisting of Mo, V, W, Ti, Cr, Mn, Fe, Co, Ni, Cu, Nb, Ta. In a yet preferred embodiment, the metal(s) of the amorphous (bi)metal sulfide nanoparticles of the invention is chosen in the group consisting of Mo and W, optionally in combination with (when the amorphous (bi)metal sulfide is an amorphous bi-metal sulfide) another element preferably chosen in the group consisting of Mo, W, Fe, Co.