TY - JOUR
T1 - Hexagonal SiC with spatially separated active sites on polar and nonpolar facets achieving enhanced hydrogen production from photocatalytic water reduction
AU - Wang, Da
AU - Liu, Ning
AU - Guo, Zhongnan
AU - Wang, Wenjun
AU - Guo, Liwei
AU - Yuan, Wenxia
AU - Chen, Xiaolong
N1 - Publisher Copyright:
© the Owner Societies 2018.
PY - 2018
Y1 - 2018
N2 - Sufficient spatial separation of photo-generated electrons and holes plays a significant role in affecting the efficiency for solar energy conversion. Non-equivalent facets of a catalyst are known to possess different charge distribution properties. Here, we report that hexagonal 6H-SiC, a metal-free, environmentally friendly, polar semiconductor, exhibits different charge distribution and photocatalytic properties on naturally occurring Si-{0001} and {10-10} facets. Very strong selectivity of metals in situ photodeposition occurs in these two facets, demonstrating that the photo-excited electrons are assembled only on polar Si-{0001} facets while the holes are assembled on non-polar {10-10} facets. Consequently, reduction reactions occur only on the Si-{0001} facets with noble metals, and meantime oxidation occurs only in {10-10} with metal oxide. We show that the activity of photocatalytic water splitting is significantly enhanced by this kind of selective depositions resulting from the charge spatial separation. The underlying mechanism is investigated in terms of experimental evidence and first principles calculations. Our results demonstrate that the utilization of facets with opposite catalytic characteristics could be a feasible means to enhance the photocatalytic performance in diverse semiconducting materials. This is, in particular, of interest for polar semiconductors, as their particles always naturally occur in both polar facets and non-polar ones without needing facet engineering.
AB - Sufficient spatial separation of photo-generated electrons and holes plays a significant role in affecting the efficiency for solar energy conversion. Non-equivalent facets of a catalyst are known to possess different charge distribution properties. Here, we report that hexagonal 6H-SiC, a metal-free, environmentally friendly, polar semiconductor, exhibits different charge distribution and photocatalytic properties on naturally occurring Si-{0001} and {10-10} facets. Very strong selectivity of metals in situ photodeposition occurs in these two facets, demonstrating that the photo-excited electrons are assembled only on polar Si-{0001} facets while the holes are assembled on non-polar {10-10} facets. Consequently, reduction reactions occur only on the Si-{0001} facets with noble metals, and meantime oxidation occurs only in {10-10} with metal oxide. We show that the activity of photocatalytic water splitting is significantly enhanced by this kind of selective depositions resulting from the charge spatial separation. The underlying mechanism is investigated in terms of experimental evidence and first principles calculations. Our results demonstrate that the utilization of facets with opposite catalytic characteristics could be a feasible means to enhance the photocatalytic performance in diverse semiconducting materials. This is, in particular, of interest for polar semiconductors, as their particles always naturally occur in both polar facets and non-polar ones without needing facet engineering.
UR - http://www.scopus.com/inward/record.url?scp=85042182878&partnerID=8YFLogxK
U2 - 10.1039/c7cp08363g
DO - 10.1039/c7cp08363g
M3 - Article
C2 - 29383351
AN - SCOPUS:85042182878
SN - 1463-9076
VL - 20
SP - 4787
EP - 4792
JO - Physical Chemistry Chemical Physics
JF - Physical Chemistry Chemical Physics
IS - 7
ER -