Exploring the effect of partial B-site Al³⁺–Mg²⁺ dual substitution on optoelectronic, surface, and photocatalytic properties of BaTaO₂N

Abstract

BaTaO2N is appraised to be one of the few promising 600 nm-class photocatalysts for solar water splitting. However, the presence of structural defects and low charge separation limits its photocatalytic...

Perovskite BaTaO2N: From Materials Synthesis to Solar Water Splitting

“…Partial Al 3+ –Mg 2+ dual substitution (5%) was applied to engineer structural defects and to modulate optoelectronic and surface properties and photocatalytic activity of BaTaO 2 N. [ 174 ] The optical absorption edge of BaTaO 2 N shifted to shorter wavelengths after (co)substitution of Al 3+ and/or Mg 2+ for Ta 5+ , leading to the increase in the optical bandgap energy. This effect was more pronounced in the BaTaO 2 N samples with higher levels of Mg 2+ dopant because a large number of O 2− were substituted for N 3− to compensate charge balance.…”

“…Reproduced with permission. [ 174 ] Copyright 2022, The Royal Society of Chemistry. Photocatalytic H 2 evolution rates of Na–Pt/BaTaO 2 N doped with various metal cations with an M/Ta ratio of 0.01 (c) and Na–Pt/BaTaO 2 N:Zr with different Zr/Ta molar ratios (d) in an aqueous solution containing methanol (15 vol%).…”

“…Under simulated AM 1.5G sunlight, a photocurrent density of ≈18 mA cm −2[ 67 ] and a solar‐to‐hydrogen (STH) conversion efficiency of about 24% [ 10 ] can be theoretically achieved for BaTaO 2 N. However, the experimentally obtained results are much lower than the predicted values due to unsuitable surface states, photocorrosion, and various types of defects formed during the synthesis process. Bandgap engineering through mono and dual substitution, [ 133,174 ] solid solutions, [ 177,185 ] defect density control, [ 124,129,150,169 ] thin film fabrication, [ 117,151 ] and the optimization of exposed surfaces, particle morphology, porosity, and size [ 131,134 ] have been explored to enhance the photoelectrochemical performance of BaTaO 2 N.…”

“…Reproduced with permission. [174] Copyright 2022, The Royal Society of Chemistry. Photocatalytic H 2 evolution rates of Na-Pt/BaTaO 2 N doped with various metal cations with an M/Ta ratio of 0. .…”

“…Under simulated AM 1.5G sunlight, a photocurrent density of ≈18 mA cm −2 [67] and a solar-to-hydrogen (STH) conversion efficiency of about 24% [10] can be theoretically achieved for BaTaO 2 N. However, the experimentally obtained results are much lower than the predicted values due to unsuitable surface states, photocorrosion, and various types of defects formed during the synthesis process. Bandgap engineering through mono and dual substitution, [133,174] solid solutions, [177,185] defect density control, [124,129,150,169] thin film fabrication, [117,151] and the optimization of exposed surfaces, particle morphology, porosity, and size [131,134] have been explored to enhance the photoelectrochemical performance of BaTaO 2 N. Remarkable advances have been made, progressively increasing the photocurrent densities for BaTaO 2 N to ≈0.03 mA cm −2 , [180] >1.2 mA cm −2 , [175] 2.05 mA cm −2 , [209] 4.2 mA cm −2 , [67] ≈4.5 mA cm −2 , [196] and 6.5 mA cm −2 [135] at 1.2 V versus RHE (Table 3, Figure 26a). Similarly, the incident photon to current conversion efficiency (IPCE) has been steadily improved with values of 1% at 500 nm, [180] >4% at 400 nm, [175] 13% at 420 nm, [209] ≈30% at 400 nm, [67] 34-35% at 380-540 nm [196] and ≈43% at 540 nm [135] at 1.2 V versus RHE (Table 3, Figure 26b).…”