Charting Ba-Based Double Perovskite Oxides for Visible-Light-Driven Photocatalytic Water Splitting

Abstract

Realizing green hydrogen generation is contingent on developing low-cost, ecofriendly, and viable photocatalysts for water splitting. Using first-principles screening, we filtered out several Ba-based double perovskites (i.e., Ba 2 BB′O 6 ) that are desired for such applications. Detailed chemical and electronic structure analyses reveal that all of the studied double perovskites, despite their disparate compositions, fall into five classes, depending on the orbital occupancy of the B and B′ cations. Of the five different classes, class I with the B = B′ = d 10 s 0 electronic configuration has proper band gap ranges (1.4−2.8 eV) and significant optical absorption coefficients, making them viable photocatalysts for visible-light-driven one-and two-photon watersplitting reactions. Among the materials examined, Ba 2 AgIO 6 , Ba 2 CdTeO 6 , Ba 2 InSbO 6 , and Ba 2 BiSbO 6 , the only class V materials, stand out for their favorable optical absorptions and low exciton binding energies. The other classes include perovskites with large band gaps (>3 eV) that are suggested as transparent anode and cathode shields to protect photocatalysts from corrosion. Our findings provide valuable insights into exploring a rich family of nontoxic, highly effective Ba-based double perovskites for photocatalytic water-splitting applications.

First-principles investigation of the structural stability, electronic, and thermodynamic properties of Ba2NaHaO6 (Ha = Cl, Br, I) periodate double perovskites

“…87 Bazrafshan et al calculated 28 barium-based DPs (Ba 2 BB′O 6 ) with different B and B′ and found their band gaps in the range 0.1–3.4 eV. 39 Our calculated band gaps are in line with these results.…”

“…36 Ba 2 BB′O 6 is usually referred to as barium-based DP due to the dominating role of Ba in the structure. 37–40 Hossain et al illustrated that when A-sites are substituted with Ba cations, the structure tends to crystallize as a high-symmetry cubic cell with an Fm 3 m space group, emphasizing the elemental character of Ba cations. 37 Kubel et al illustrated the structural differences in M 2 NaIO 6 (M = Ca, Sr, Ba) DPs due to M cations and pointed out the cubic structure for Ba at A sites.…”

“…They found that the barium-based DPs with different B and B′ exhibit band gaps in the range 0.1–3.4 eV. 39 Kazim et al also studied “barium-based” DPs, Ba 2 XIO 6 (X = Ag, Na). They reported the band gaps of 1.9 eV and 3.2 eV and the figure of merit ( ZT ) values of 0.63 and 0.75 as calculated with mBJ potentials for X = Ag and Na, respectively, and emphasized their potential in optoelectronic and thermoelectric applications.…”