Manipulating interface built-in electric fields for efficient spatial charge separation in hematite-based photoanodes

Abstract

Herein, a novel strategy of interface charge modulation for manipulating interface built-in electric fields (IEFs) and boosting spatial charge separation is introduced to alleviate charge recombination in the bulk and at the surface of hematite photoanodes. Hydrothermally grown Ti-doped hematite (Hem) nanorods are decorated with graphitic carbon nitride (g-C 3 N 4 ) species and small molybdenum oxide (MoO 3 ) clusters using a facile two-step dip-coating process. Compared with the pristine Hem, the obtained Hem/C 3 N 4 /MoO 3 exhibits increased photoelectrochemical water splitting performance with its photoanodic current density remarkably increased from 0.3 to 1.6 mA cm −2 at 1.23 V versus reversible hydrogen electrode (RHE) and incident photon-to-current conversion efficiency reaching 18.4% at 1.23 V versus RHE at 300 nm. The IEFs are introduced in the Hem/C 3 N 4 /MoO 3 heterojunction by modulating the interfacial charge property via a type II band alignment at the Hem/C 3 N 4 interface and an enhanced band bending at the surface of the photoanode, which substantially promote the spatial charge separation. By relieving the bottleneck of charge carrier transfer dynamics, this work in interfacial charge modulation provides a facile and effective strategy to boost the spatial charge separation in Hem-based photoanodes and other semiconducting devices for efficient solar energy conversion.

Photoelectrocatalytic Water Splitting by Conformal Copper‐Oxide on Hematite Nanostructures: Dependence on Surface‐States

“…[a] determined by cyclic voltammetry (CV) performed at different scan rates (ν) in the non‐Faradaic potential range (Figure S7). [b] derived from C dl by using 40 μF cm −2 as the specific capacitance for flat α ‐ Fe 2 O 3 [72,73] …”

“…[b] derived from C dl by using 40 μF cm À 2 as the specific capacitance for flat α-Fe 2 O 3 . [72,73] face during electrochemical reactions, have been also experimentally investigated. The lower C dl and ECSA values for α-Fe 2 O 3 compared to Ti : α-Fe 2 O 3 (Table 2) are expected and coherent with the presence of the Ti-dopant.…”

Analysis of Spatio-Temporal Evolution of Regional Settlements under the Background of Rapid Urbanization: A Case Study in Sishui County, China

“…An average nearest neighbor analysis is used to investigate whether the spatial distribution of point elements belongs to an aggregation, dispersion, or random pattern [32]. In this study, a mean nearest neighbor analysis is used to estimate the distribution characteristics of rural settlements in each period.…”

Photoelectrochemical water splitting by hematite boosted in a heterojunction with B-doped g-C3N4 nanosheets and carbon nanotubes

“…35,36 Doping g-C 3 N 4 with less electronegative elements, such as boron (B, giving B-C 3 N 4 ), has emerged as an efficient strategy not only to improve absorption by narrowing the band gap of g-C 3 N 4 , but also to promote the photogenerated carrier separation due to the formation of a mid-gap state. [37][38][39] Additionally, materials such as CdS, MoS 2 , CdSe, and Cu 2 O are being explored for their potential in heterostructures with g-C 3 N 4 , operating via type-II, S-scheme, or Z-scheme mechanisms to enhance hydrogen evolution via efficient charge separation and solar energy utilization. [40][41][42][43][44] A further issue may emerge from the transfer of charge carriers which is strongly inuenced by the quality of interfacial contact between different particles.…”