Band structure engineering of semiconductors for enhanced photoelectrochemical water splitting: The case ofTiO2

Abstract

Here, we propose general strategies for the rational design of semiconductors to simultaneously meet all of the requirements for a high-efficiency, solar-driven photoelectrochemical ͑PEC͒ water-splitting device. As a case study, we apply our strategies for engineering the popular semiconductor, anatase TiO 2. Previous attempts to modify known semiconductors such as TiO 2 have often focused on a particular individual criterion such as band gap, neglecting the possible detrimental consequence to other important criteria. Density-functional theory calculations reveal that with appropriate donor-acceptor coincorporation alloys with anatase TiO 2 hold great potential to satisfy all of the criteria for a viable PEC device. We predict that ͑Mo, 2N͒ and ͑W, 2N͒ are the best donor-acceptor combinations in the low-alloy concentration regime whereas ͑Nb, N͒ and ͑Ta, N͒ are the best choice of donor-acceptor pairs in the high-alloy concentration regime.

Codoping titanium dioxide nanowires with tungsten and carbon for enhanced photoelectrochemical performance

“…The PEC water-splitting performance of the codoped TiO 2 :(W, C) NWs is evaluated by measuring photocurrent density-potential (J-V) curves using a standard three-electrode configuration under air mass (AM) 1.5 G simulated solar light illumination (100 mW cm À 2 ), and compared with undoped and monodoped (W and C) TiO 2 NWs (Fig. 3a) 15,19 . To the best of our knowledge, this is the first experimental demonstration for a donor-acceptor codoped TiO 2 system that exhibits enhanced PEC water-splitting performance than monodoped TiO 2 .…”

“…Even without doping, the performance of TiO 2 -based PEC water-splitting cells is greatly limited by its rapid charge recombination due to the high trap densities in TiO 2 4 . Recently, a new donor-acceptor codoping concept was proposed to improve the PEC water-splitting performance of TiO 2 photoanode because codoping TiO 2 with donor-acceptor pairs can reduce charged defects and their associated recombination, improve material quality, enhance light absorption and increase solubility limits of dopants [15][16][17][18][19] . According to densityfunctional theory calculations, various donor-accepter pairs, such as (W, C) 15,19 , (Mo, C) 15,16,19 , (2Nb, C) 15,18 , (2Ta, C) 15,18 , (W, 2N) 15,20 , (Ta, N) 15 , (Nb, N) 15 , (Sb, N) 21 , (Cr, N) 22 , (Zr, S) 15 and (Nb, P) 15 , have been proposed as good candidates for TiO 2 codoping on the basis of the modified band gaps and band-edge positions.…”

Polymorph Engineering of TiO2: Demonstrating How Absolute Reference Potentials Are Determined by Local Coordination

“…15,[60][61][62][63] These effects should be taken into consid-eration when explaining the observable properties of all TiO 2 polymorphs.…”

Doping properties of monoclinic BiVO4studied by first-principles density-functional theory

“…On the other hand, p-type and n-type doping of metal oxides may also be realized by introducing impurities to O sites [36][37][38][39][40][41][42][43][44][45][46]. In this case, C, N, and F are the most considered impurities.…”