Bulk Embedding of Ferroelectric Nanodomains in CuBi₂O₄ Photocathodes Enables Boosted Photoelectrochemical Hydrogen Generation

Abstract

It is widely accepted that metal oxide‐based photoelectrodes (MOPs) hold great promise for future solar hydrogen generation but are facing awkward challenge arising from their low intrinsic carrier mobility. The highly polarized nature of the predominantly ionic metal‐oxygen bond always leads to the formation of small polarons that are responsible for the localized trapping of photo‐generated carriers. Present study explores the reduction of carriers transport barrier via bulk embedding of ferroelectric nanodomains (FNDs) in MOPs that results in a new performance benchmark for the CuBi2O4 photocathode. By embedding laser‐generated sub‐10 nm BaTiO3 nanocrystals in the bulk of CuBi2O4 photocathode, numerous FNDs are created that can lead to two times enhancement of the carrier mobility, which is proposed to originate from the overlaying of the internal electric fields and effective electrons transport channel at the heterointerfaces of BaTiO3/CuBi2O4. Such strategy leads to the CuBi2O4 photocathode with the photocurrent density of up to 3.21 mA cm−2 at 0.6 VRHE, as well as a pronounced absorbed photon‐to‐current efficiency up to 80% at 400 nm. The universal feature of present technology is further verified by laser embedding of SrTiO3 FNDs, providing an effective route for addressing the charge transport limitations in MOPs.

Two-dimensional Janus perovskite oxynitrides as active photocatalysts for overall water splitting with ferroelectric modulation

“…2c and S5†), which are higher than 1 eV and in good agreement with a recent report on BaTiO 3 . 62 Potential differences linearly increase from 2.78 to 5.05 eV for BaNbNO 2 and 2.73 to 4.05 eV for BaTaNO 2 with the incremental thickness, respectively (Fig. S5†).…”

Engineering Directional Charge Carrier Transport Using Ferroelectric Polarization for Enhanced Photoelectrochemical Water Oxidation

“…The ferroelectric polarization generated from ferroelectric perovskite oxides allows fine manipulation of the charge transport to reach optimal configuration for reduction and oxidation reactions. [27][28][29][30] Interestingly, the versatile tunability of ferroelectric polarization by an external electric field allows further band alignment to modify the depletion region of the photoactive semiconductors and the charge distribution at the photoelectrode surface. [31][32][33] Previous studies mainly focus on the direction and magnitude, [34][35][36] and the studies of the impact of ferroelectric polarization and electron extraction on the target application of PEC water splitting are still in their infancy.…”

Disentangling the Role of Ag‐Based Nanocorals as Efficient Cocatalyst over CuBi2O4 Photocathodes Toward Hydrogen Evolution Reaction

“…[7] However, CuBi 2 O 4 also suffers from three main drawbacks: 1) low chemical stability under aqueous conditions, as a consequence of photocorrosion, as it happens in other Cu-based photocathodes, [8] 2) low visible light absorption, [9] and 3) poor charge separation and transport properties, [10,11] leading to low photocurrent densities. Trying to overcome these limitations, several studies have explored different strategies to enhance the photoelectrocatalytic activity of CuBi 2 O 4 , including postsynthetic treatments, [12] surface modification, [13] surface protection, [3] heterostructure formation, [14,15] the introduction of ferroelectric nanodomains, [16] self-doping by the introduction of Cu vacancies, [17] external doping, [18] and cocatalyst deposition, [19] resulting in an improved photoelectrochemical performance. Specifically, MoS 2 has been reported as an effective cocatalyst toward photoelectrocatalytic H 2 production in alkaline media.…”