Design of efficient Mn-doped α-Fe2O3/Ti-doped α-Fe2O3 homojunction for catalyzing photoelectrochemical water splitting. (28th February 2020) - Tao, Shang-Mao
Abstract: To produce clean chemical fuel of hydrogen efficiently, applying photocatalysts for conducting photoelectrochemical water splitting is indispensable. Hematite (α-Fe2 O3 ) has been considered as one of the most effective photocatalysts for water oxidation due to excellent visible-light responses, high stability and source abundance properties, but low electrical conductivity and slow oxidation evolution kinetics limit its application. In this study, a novel α-Fe2 O3 homojunction is constructed via doping Ti and Mn in two layers using two-step hydrothermal synthesis followed by one-step annealing process. Co-doping effect of Ti and Mn in α-Fe2 O3 and growing sequence of Mn doped α-Fe2 O3 (Mn:Fe2 O3 ) and Ti doped α-Fe2 O3 (Ti:Fe2 O3 ) are also investigated to illustrate the efficient design of Mn:Fe2 O3 /Ti:Fe2 O3 homojunction. The optimized Mn:Fe2 O3 /Ti:Fe2 O3 electrode shows the highest photocurrent density of 2.10 mA/cm 2 at 1.60 VRHE respectively comparing to those of 0.10, 1.20 and 0.22 mA/cm 2 for Ti:FeOOH, Ti:Fe2 O3 and α-Fe2 O3 electrodes. The outstanding performance of Mn:Fe2 O3 /Ti:Fe2 O3 homojunction is attributed to the smaller charge-transfer resistance, higher carrier density, and less charge recombination. This work gives a rational design for hematite-based photocatalysts and successfully attains greatly improved photocatalytic ability for water oxidation. Development of homojunction using heteroatom doping in thus verified to be highly applicable on synthesizing promising photocatalysts. Graphical abstract: Image 1 Highlights: Novel α-Fe2 O3 homojunction is made by doping Ti and Mn using a hydrothermal process. α-Fe2 O3 homojunction electrode with Ti/Mn doping is used to catalyze water splitting. Co-doping effect and growing sequence of Mn and Ti-doped α-Fe2 O3 layer are studied. Mn:Fe2 O3 /Ti:Fe2 O3 electrode shows a photocurrent density of 2.10 mA/cm 2 at 1.60 VRHE . Due to small charge-transfer resistance, high carrier density and less recombination.