Graded catalytic-protective layer for an efficient and stable water-splitting photocathode
View Patent ↗The present disclosure relates to a composition that includes, in order: a first layer that includes MA w ; a second layer that includes MO y A z ; and a third layer that includes MO x , where M includes a transition metal, A includes at least one of sulfur, selenium, and/or tellurium, w is between greater than zero and less than or equal to five, x is between greater than zero and less than or equal to five, y is between greater than zero and less than or equal to five, and z is between greater than zero and less than or equal to five. In some embodiments of the present disclosure, the transition metal may include at least one of molybdenum and/or tungsten. In some embodiments of the present disclosure, A may be sulfur.
1. A composition comprising, in order:
a first layer comprising MA w ;
a second layer comprising MO y A z ; and
a third layer comprising MO x , wherein:
M comprises a transition metal,
A comprises at least one of sulfur, selenium, or tellurium,
w is between greater than zero and less than or equal to five,
x is between greater than zero and less than or equal to five,
y is between greater than zero and less than or equal to five, and
z is between greater than zero and less than or equal to five.
2. The composition of claim 1 , wherein the transition metal comprises at least one of molybdenum or tungsten.
3. The composition of claim 1 , wherein A is sulfur.
4. The composition of claim 1 , wherein the first layer comprises MoS w .
5. The composition of claim 1 , wherein the second layer comprises MoO y S z .
6. The composition of claim 1 , wherein the third layer comprises MoO x .
7. The composition of claim 1 , wherein w is between greater than one and less than or equal to three.
8. The composition of claim 1 , further comprising:
a first transition layer positioned between the first layer and the second layer, wherein:
the transition layer contains intermixed MA w and MO y A z .
9. The composition of claim 1 , further comprising:
a first transition layer positioned between the second layer and the third layer, wherein:
the transition layer contains intermixed MO y A z and MO x .
10. The composition of claim 1 , wherein the first layer, the second layer, and the third layer are all at least partially intermixed.
11. The composition of claim 1 , wherein at least one of the first layer, the second layer, and the third layer is at least partially crystalline.
12. The composition of claim 1 , wherein the first layer has a thickness between 1 μm and 100 μm.
13. The composition of claim 1 , wherein the second layer has a thickness between 1 μm and 100 μm.
14. The composition of claim 1 , wherein the third layer has a thickness between 1 μm and 100 μm.
15. The composition of claim 1 , further comprising:
an oxide layer, wherein the third layer is positioned between the oxide layer and the second layer.
16. The composition of claim 15 , wherein the oxide layer comprises at least one of titanium oxide, aluminum oxide, or zinc oxide.
17. The composition of claim 15 , further comprising:
an active layer comprising a group III-V alloy, wherein the oxide layer is positioned between the active layer and third layer.
18. A method comprising, in order:
depositing a starting layer comprising MA v onto an oxide layer; and annealing the starting layer and the oxide layer, wherein:
v is between greater than zero and less than or equal to five, and
the annealing transforms the starting layer to a graded layer comprising, in order:
a first layer comprising MA w ;
a second layer comprising MO y A z ; and
a third layer comprising MO x , wherein:
M comprises a transition metal,
A comprises at least one of sulfur, selenium, or tellurium,
w is between greater than zero and less than or equal to five,
x is between greater than zero and less than or equal to five,
y is between greater than zero and less than or equal to five, and
z is between greater than zero and less than or equal to five.
19. The method of claim 18 , wherein the depositing is performed by electrochemical cathodic deposition.
20. A method for photoelectrochemical water-splitting, the method comprising:
contacting a device with water; and
exposing the device to a lightsource, wherein:
the contacting and the exposing convert at least a portion of the water to hydrogen, and
the device comprises:
a first layer comprising MA w ;
a second layer comprising MO y A z ; and
a third layer comprising MO x , wherein:
A comprises a transition metal,
w is between greater than zero and less than or equal to five,
x is between greater than zero and less than or equal to five,
y is between greater than zero and less than or equal to five, and
z is between greater than zero and less than or equal to five.