Nature of Catalytic Active Surface Sites on Semiconductor Photocatalysts for Splitting of Water

Meeting Program — March 2013

Som­phonh Peter Phivi­lay
Operan­do Mol­e­c­u­lar Spec­troscopy & Catal­y­sis Lab­o­ra­to­ry
Depart­ment of Chem­i­cal Engi­neer­ing
Lehigh Uni­ver­si­ty
Beth­le­hem, PA 18015 USA
Stu­dent Speak­er

Abstract — One of society’s great chal­lenges for the 21st cen­tu­ry is the devel­op­ment of alter­na­tive ener­gy resources. Hydro­gen is con­sid­ered to be one of the poten­tial can­di­dates espe­cial­ly if it can be gen­er­at­ed from the pho­to­cat­alyt­ic con­ver­sion of cheap abun­dant H2O into clean non-car­bon H2 from solar ener­gy resources. Devel­op­ment of this clean, renew­able form of ener­gy will help to address our reliance on deplet­ed fos­sil fuel sup­plies and the envi­ron­men­tal prob­lems accom­pa­ny­ing its use.

Pho­to­cat­alyt­ic split­ting of waters pro­ceeds via gen­er­a­tion of excit­ed elec­trons and holes in the semi­con­duc­tor cat­a­lyst bulk lat­tice, the dif­fu­sion of the exci­tons through the semi­con­duc­tor lat­tice to the sur­face, and sur­face reac­tions of the exci­tons with water to split H2O to H2 and O2. The pho­to­catal­y­sis lit­er­a­ture, how­ev­er, has almost com­plete­ly neglect­ed the sur­face nature of pho­to­cat­a­lysts and focused on the semi­con­duc­tor cat­a­lyst bulk lat­tice that is only respon­si­ble for gen­er­a­tion of the excit­ed holes and elec­trons.

This pre­sen­ta­tion will exam­ine the anato­my of the sup­port­ed (Rh2-yCryO3)/(Ga1-xZnx)(N1-xOx) pho­to­cat­a­lysts that are able to split water with vis­i­ble light exci­ta­tion by deter­min­ing the nature of the bulk lat­tice (mm), sur­face region (~1–3 nm) and out­er­most sur­face lat­er (~0.3 nm) with unique cut­ting edge char­ac­ter­i­za­tion tech­niques.