Directional Charge Transfer Channels in a Monolithically Integrated Electrode for Photoassisted Overall Water Splitting

Abstract

Photoelectrocatalytic performance of a system is fundamentally determined by the full absorption of sunlight and high utilization of photoexcited carriers, but efficiency of the latter is largely limited by inefficient charge transfer from the absorber to reactive sites. Here, we propose to construct directional charge transfer channels in a monolithically integrated electrode, taking carbon dots/carbon nitride (CCN) nanotubes and FeOOH/FeCo layered double hydroxide (FFC) nanosheets as a representative, to boost the photoassisted overall water splitting performance. Detailed experimental investigations and DFT calculations demonstrate that the interfacial C–O–Fe bonds between CCN and FFC act as charge transfer channels, facilitating the directional migration of the photogenerated carriers between CCN and FFC surfaces. Moreover, the in situ oxidized Fe/Co species by photogenerated holes trigger lattice oxygen activation, realizing the construction of the Fe–Co dual-site as the catalytic center and efficiently lowering the barrier energy for water oxidation. As a result, the CCN@FFC electrode shows multiple functionalities in photoelectrocatalysis: only a low overpotential of 68 mV, 182 mV, and 1.435 V is required to deliver 10 mA cm–2 current densities for the photoassisted HER, OER, and overall water splitting, respectively. This directional charge transfer modulation strategy may facilitate the design of highly active and cost-effective multifunctional catalysts for energy conversion and storage.

Interlayer Structure and Chemistry Engineering of MXene-Based Anode for Effective Capture of Chloride Anions in Asymmetric Capacitive Deionization

“…These facts prove that oxygen evolution reactions are inhibited in MBP composite film electrodes. The same trend is also observed when using 20 mM NaCl as the electrolyte, as shown in Figure S6. , All of these results prove that the integration of BC@PPy endows MBP with anti-oxidation properties and enables MBP to tolerate high oxidation potentials.…”

Formulating a heterolytic cleavage process of water on Ni3N nanosheets through single transition metal doping for ultra-efficient alkaline hydrogen evolution

“…filling (higher occupation) of anti-bonding states between the adsorbate and d band of the catalyst, leading to weakened interaction between the adsorbate and the surface as described by UPS analysis. [1][2][3][4] A possible mechanism, based on the above analyses, of the V-Ni 3 N system for the alkaline HER is summarized in Fig. 4f.…”

“…Hydrogen is widely regarded as an eco-friendly and renewable energy, which can help people reduce excessive dependence on fossil fuels. [1][2][3] Although electrochemical water splitting has been industrialized for many decades, it is still a highly intensive energy-consuming technology. [4][5][6] Regarding the hydrogen evolution reaction (HER) in alkaline media, as a half-reaction of the total hydrolysis reaction, there are two existing drawbacks: its sluggish kinetics because of the need for extra energy to yield protons by water dissociation (Volmer step), and the requirement of optimized hydrogen adsorption energy.…”

Integration of Ag Plasmonic Metal and WO3/InGaN Heterostructure for Photoelectrochemical Water Splitting

“…Hydrogen production through photoelectrochemical (PEC) water splitting using sunlight has emerged as an attractive renewable approach for a green economy. , However, achieving high solar-to-hydrogen (STH) conversion efficiency is crucial and involves rapid charge carrier separation and charge carrier transfer. Due to the intrinsic wide bandgap of semiconductors (SCs), solar energy conversion efficiency remains low, and there is a need to investigate narrow-bandgap materials for enhanced conversion efficiency. , Heterogeneous semiconductor-based photocatalysis has gained increasing attention for its potential to improve photoabsorption and reduce charge carrier recombination rates, leading to better PEC performance. , Ever since Fujishima and Honda et al demonstrated the use of TiO 2 as a photoanode for hydrogen production under UV light, numerous semiconductors such as ZnO (∼3.2 eV), TiO 2 (∼3.2 eV), Cu 2 O (∼2.4 eV), WO 3 (∼2.8 eV), BiVO 4 (∼2.4 eV), and α-Fe 2 O 3 (∼1.9–2.2 eV), ZnFe 2 O 4 /TiO 2 , g-C 3 N 4 (∼2.7–2.9 eV), carbo-nitride nanotubes, etc. were exploited for PEC water splitting.…”

“…4,5 Heterogeneous semiconductor-based photocatalysis has gained increasing attention for its potential to improve photoabsorption and reduce charge carrier recombination rates, leading to better PEC performance. 6,7 Ever since Fujishima and Honda et al demonstrated the use of TiO 2 as a photoanode for hydrogen production under UV light, 8 numerous semiconductors such as ZnO (∼3.2 eV), 9 TiO 2 (∼3.2 eV), 10 Cu 2 O (∼2.4 eV), 11 WO 3 (∼2.8 eV), 12 BiVO 4 (∼2.4 eV), 13 and α-Fe 2 O 3 (∼1.9−2.2 eV), 14 ZnFe 2 O 4 /TiO 2 , 15 g-C 3 N 4 (∼2.7−2.9 eV), 16 carbonitride nanotubes, 17 etc. were exploited for PEC water splitting.…”