Solar‐Light‐Driven Pure Water Splitting with Ultrathin BiOCl Nanosheets

Abstract

A suitable photocatalyst for overall water splitting has been produced by overcoming the disadvantage of the band structure in bulk BiOCl by reducing the thickness to the quantum scale. The ultrathin BiOCl nanosheets with surface/subsurface defects realized the solar-driven pure water splitting in the absence of any co-catalysts or sacrificial agent. These surface defects cannot only shift both the valence band and conduction band upwards for band-gap narrowing but also promote charge-carrier separation. The amount of defects in the outer layer surface of BiOCl results in an enhancement of carrier density and faster charge transport. First-principles calculations provide clear evidence that the formation of surface oxygen vacancies is easier for the ultrathin BiOCl nanosheets than for its thicker counterpart. These defects can serve as active sites to effectively adsorb and dissociate H2 O molecules, resulting in a significantly improved water-splitting performance.

Sillén–Aurivillius-related Oxychloride Bi6NbWO14Cl as a Stable O2-evolving Photocatalyst in Z-scheme Water Splitting under Visible Light

“…above-estimated CBM, which is slightly higher than the water reduction potential. Figure 4 shows the time courses of O 2 evolution from water on Bi 6 15 The rate of O 2 evolution from AgNO 3 (aq) is comparable to that of the previous Bi 4 NbO 8 Cl, in marked contrast to Bi 2 WO 6 and BiOCl that showed negligibly low activity ( Figure S8). The rate of O 2 evolution on Bi 6 NbWO 14 Cl in FeCl 3 (aq) is much lower than that in AgNO 3 (aq), which is probably due to the occurrence of backward reaction, i.e., reoxidation of Fe 2+ to Fe 3+ by photogenerated holes.…”

“…The VBM of this compound is located at a much more negative level than those of Bi 2 WO 6 and BiOCl, resulting in the smaller band gap of ca. 2.5 eV, though it is slightly larger than ca.…”

“…1,2 Over the past decades, various mixed-anion compounds such as oxynitrides, 3,4 oxysulfides, 5 and oxyhalides 6 have been extensively studied as promising candidates. The valence band maximum (VBM) of these mixed-anion semiconductors is generally more negative than that of oxide counterparts due to the p orbitals of non-oxide anions (e.g., N 3¹ , S 2¹ , Br ¹ , or I ¹ ) being located at a higher energy, which results in the band gap to be narrowed and affords visible light absorption.…”

Recent Advances in Bismuth‐Based Nanomaterials for Photoelectrochemical Water Splitting

“…[59] Notably,a fter the introduction of oxygen vacancies in the (0 01)a nd (0 10)p lanes of BiOCl, this material exhibits different relaxation behavior.A s projected in Figure 3b,c for the (0 01)s urface of BiOCl, the Bi-Cl bond length relaxes parallel to (0 01), whereas the BiÀCl bond lengths hortens by undergoing out-of-plane relaxation. [34,[60][61][62][63][64] The optical band gap of BiOCl is 3.2 eV.T he valence band minimum consists of Bi 6s and O2ph ybridized orbitals, which are suitable for water oxidation. [34] However,B iOX materials are seldom investigated for PEC water splitting.…”

Novel one-pot synthesis and sensitisation of new BiOCl–Bi2S3 nanostructures from DES medium displaying high photocatalytic activity

“…It is its size, shape and surface structure which will, ultimately, control their optical and photocatalytic properties and therefore its suitability to distinct purposes. For example, BiOCl has shown ability to water splitting reaction under solar light irradiation [1][2][3] , photocatalytic activity to the degradation of dyes and other pollutants under ultra-violet (UV) and visible radiation [4][5][6][7][8][9][10][11] , UV photodetectors 12 , to be used as catalyst for air electrode of aluminium-air batteries 13 and as an anode material for sodium-ion batteries. 14 BiOCl has a tetragonal structure, formed by layers of [Bi2O2] 2+ intercalated with a double layer of chloride ions accommodated in the interlayers, with interlayer distance of 7.38 Å.…”