Catalytic pom particles

Abstract

POM particles are suitable as photocatalytic or electrocatalytic catalyst in the production of hydrogen and a method of producing such POM particles. The POM particles are produced by subjecting a heteropoly acid with the chemical formula HzXY12O40, or a hydrate thereof, to acidic conditions in the presence of a polyvalent cation, wherein z=3 or 4, X is selected from the group consisting of P, Si, Ge, As, Sb and V, and Y is selected from the group consisting of W, Mo and V.

1 . A method of producing polyoxometalate (POM) particles, the method comprising producing the POM particles by subjecting a heteropoly acid with the chemical formula H z XY 12 O 40 , or a hydrate thereof, to acidic conditions in the presence of a polyvalent cation, wherein z=3 or 4, X is selected from the group consisting of P, Si, Ge, As, Sb and V, and Y is selected from the group consisting of W, Mo and V. 
     
     
         2 . The method according to  claim 1 , wherein producing the POM particles comprises heating the heteropoly acid, or the hydrate thereof, while exposed to the acidic conditions in the presence of the polyvalent cation. 
     
     
         3 . The method according to  claim 1 , wherein producing the POM particles comprises producing the POM particles in a sol-gel process by subjecting the heteropoly acid, or the hydrate thereof, to the acidic conditions in the presence of the polyvalent cation causing individual POMs to aggregate to form nanoparticles, which assemble into ternary particles. 
     
     
         4 . The method according to  claim 1 , wherein the polyvalent cation is selected from the group consisting of Ti(IV), Zr(IV), Ce(IV), La(III), Ce(III), Pr(III), Nd(III), Sm(III), Eu(III), Gd(III), Tb(III), Dy(III), Ho(III), Er(III), Tm(III), Yb(III), Lu(III), Sc(III) and Y(III). 
     
     
         5 . The method according to  claim 4 , wherein the polyvalent cation is selected from the group consisting of Ti(IV) and La(III). 
     
     
         6 . The method according to  claim 1 , wherein a molar ratio of the heteropoly acid, or the hydrate thereof, and the polyvalent cation is selected within an interval of 1:0.25 to 1:2. 
     
     
         7 . The method according to  claim 1 , wherein producing the POM particles comprises mixing the heteropoly acid, or the hydrate thereof, and an acidic solution comprising the polyvalent cation. 
     
     
         8 . The method according to  claim 1 , wherein the heteropoly acid is phosphotungstic acid H 3 PW 12 O 40 . 
     
     
         9 . The method according to  claim 1 , wherein the subjecting the heteropoly acid, or the hydrate thereof, to acidic conditions comprises subjecting the heteropoly acid, or the hydrate thereof to the polyvalent cation at a pH equal to or below 0.5. 
     
     
         10 . The method according to  claim 1 , further comprising isolating the POM particles by filtration. 
     
     
         11 . The method according to  claim 1 , wherein the POM particles are nanostructured microparticles. 
     
     
         12 . The method according to  claim 11 , wherein POM nanoparticles have average diameter selected within an interval of from 5 nm up to 50 nm. 
     
     
         13 . The method according to  claim 1 , wherein the POM particles have an average diameter of at least 0.5 μm. 
     
     
         14 . Polyoxometallate (POM) particles comprising a heteropoly acid with the chemical formula H z XY 12 O 40 , or a hydrate thereof, and a polyvalent cation, wherein z=3 or 4, X is selected from the group consisting of P, Si, Ge, As, Sb and V, and Y is selected from the group consisting of W, Mo and V. 
     
     
         15 . The POM particles according to  claim 14 , wherein the polyvalent cation is selected from the group consisting of Ti(IV), Zr(IV), Ce(IV), La(III), Ce(III), Pr(III), Nd(III), Sm(III), Eu(III), Gd(III), Tb(III), Dy(III), Ho(III), Er(III), Tm(III), Yb(III), Lu(III), Sc(III) and Y(III). 
     
     
         16 . The POM particles according to  claim 15 , wherein the polyvalent cation is selected from the group consisting of Ti(IV) and La(III). 
     
     
         17 . The POM particles according to  claim 14 , wherein the heteropoly acid is phosphotungstic acid H 3 PW 12 O 40 . 
     
     
         18 . The POM particles according to  claim 14 , wherein the POM particles are nanostructured microparticles. 
     
     
         19 . The POM particles according to  claim 18 , wherein POM nanoparticles have average diameter selected within an interval of from 5 nm up to 50 nm. 
     
     
         20 . The POM particles according to  claim 14 , wherein the POM particles have an average diameter of at least 0.5 μm. 
     
     
         21 . The POM particles according to  claim 14 , wherein the POM particles are obtainable by a method comprising producing the POM particles by subjecting a heteropoly acid with the chemical formula H z XY 12 O 40 , or a hydrate thereof, to acidic conditions in the presence of a polyvalent cation, wherein z=3 or 4, X is selected from the group consisting of P, Si, Ge, As, Sb and V, and Y is selected from the group consisting of W, Mo and V. 
     
     
         22 . An electrocatalytic water-splitting device comprising:
 a working electrode comprising POM particles according to  claim 14 ;   a counter electrode; and   a reference electrode.   
     
     
         23 . A method of producing hydrogen gas comprising producing hydrogen gas by photocatalytic or electrocatalytic water composition in the presence of a photocatalytic or electrocatalytic catalyst comprising POM particles according to  claim 14 .