Film of graphitic carbon nitride for photoanode and a method for forming the same
A method for forming a film of graphitic carbon nitride (g-CN) by way of thermal vapor condensation comprising the steps of: a) providing a solid-phase thiourea precursor and a solid-phase melamine precursor in a container; b) covering the container with a first substrate; and c) thermally generating a vapor-phase thiourea source and a vapor-phase melamine source from the solid-phase thiourea precursor and the solid-phase melamine precursor in an air environment thereby forming a layer of g-CN on the first substrate. A film of g-CN formed by the method is also addressed.
1 . A method for forming a film of graphitic carbon nitride (g-CN) by way of thermal vapor condensation comprising the steps of:
a) providing a solid-phase thiourea precursor and a solid-phase melamine precursor in a container;
b) covering the container with a first substrate; and
c) thermally generating a vapor-phase thiourea source and a vapor-phase melamine source from the solid-phase thiourea precursor and the solid-phase melamine precursor in an air environment thereby forming a layer of g-CN on the first substrate;
wherein the solid-phase thiourea precursor and the solid-phase melamine precursor are physically separated by a support substrate.
2 . The method as claimed in claim 1 , wherein the support substrate is positioned at an angle relative to a side of the container.
3 . The method as claimed in claim 2 , wherein the support substrate comprises a layer of solid-phase thiourea precursor.
4 . The method as claimed in claim 3 , further comprising the step of forming the layer of solid-phase thiourea precursor.
5 . The method as claimed in claim 4 further comprising the steps of:
heating thiourea solid in deionized water to form a hot saturated thiourea solution;
forming a layer of saturated thiourea on the support substrate by at least partially immersing the support substrate in the saturated thiourea solution; and
drying the layer of saturated thiourea to obtain the solid-phase thiourea precursor.
6 . The method as claimed in claim 5 , wherein the step of drying the layer of saturated thiourea solution is conducted under ambient conditions.
7 . The method as claimed in claim 5 , wherein the thiourea solid in deionized water is heated to a temperature of about 60° C. to about 150° C.
8 . The method as claimed in claim 5 , wherein the support substrate is at least partially immersing in the saturated thiourea solution for about 2-15 seconds.
9 . The method as claimed in claim 5 , wherein the layer of solid-phase thiourea precursor has a thickness of about 1.5 mm.
10 . The method as claimed in claim 5 , wherein the layer of solid-phase thiourea has a weight of about 0.6 g.
11 . The method as claimed in claim 1 , wherein the solid-phase melamine precursor has a weight of about 1 g to about 5 g.
12 . The method as claimed in claim 1 , wherein step c) includes the steps of:
annealing the solid-phase thiourea precursor and the solid-phase melamine precursor to generate the vapor-phase thiourea source comprising active carboiimide species and the vapor-phase melamine source; and
allowing the vapor-phase thiourea source and the vapor-phase melamine source to deposit and react to form the layer of g-CN on the first substrate.
13 . The method as claimed in claim 12 , wherein the annealing step is conducted in a muffle furnace at about 550° C. for about 3 hours, with a heating rate of about 3° C./min.
14 . The method as claimed in claim 1 further comprising step d) post-annealing the layer of g-CN formed in step c).
15 . The method as claimed in claim 14 , wherein step d) is conducted in a muffle furnace at about 300° C. for about 30 min, with a heating rate of about 3° C./min.
16 . The method as claimed in claim 1 , wherein the first substrate comprises a FTO glass.
17 . The method as claimed in claim 1 , wherein the support substrate comprises a glass strip.
18 . The method as claimed in claim 1 , wherein the container is polished.
19 . The method as claimed in claim 18 further comprising the step of polishing the container rim successively with an abrasive from about 400 Cw to about 1200 Cw.
20 . The method as claimed in claim 1 further comprising the step of placing a load on top of the first substrate for minimizing leakage of the vapor-phase thiourea source and a vapor-phase melamine source.
21 . The method as claimed in claim 1 , wherein each of the solid-phase thiourea precursor and the solid-phase melamine precursor is in powder form.
22 . The method as claimed in claim 21 further comprising the steps of:
preparing a homogeneous mixture of the solid-phase thiourea precursor and the solid-phase melamine precursor by grinding thiourea solid and melamine solid; and
transferring the homogeneous mixture to the container for thermal treatment.
23 . The method as claimed in claim 22 , wherein the thiourea solid and the melamine solid has a weight ratio of about 1-3:3.
24 . The method as claimed in claim 22 , wherein step c) comprises the steps of:
annealing the solid-phase thiourea precursor and the solid-phase melamine to generate the vapor-phase thiourea source and the vapor-phase melamine source; and
allowing the vapor-phase thiourea source and the vapor-phase melamine source to deposit and react to form the layer of g-CN on the first substrate.
25 . The method as claimed in claim 24 , wherein the annealing step is conducted in a muffle furnace at about 500° C. to about 550° C. for about 3 hours, with a heating rate of about 3° C./min.