Engineering MoO_x/MXene Hole Transfer Layers for Unexpected Boosting of Photoelectrochemical Water Oxidation

Abstract

The development of semiconductor photoanodes is of great practical interest for the realization of photoelectrochemical (PEC) water splitting. Herein, MXene quantum dots (MQD) were grafted on a BiVO 4 substrate, then a MoO x layer by combining an ultrathin oxyhydroxide oxygen evolution cocatalyst (OEC) was constructed as an integrated photoanode. The OEC/ MoO x /MQD/BiVO 4 array not only achieves a current density of 5.85 mA cm À 2 at 1.23 V versus a reversible hydrogen electrode (vs. RHE), but also enhances photostability. From electrochemical analysis and density functional theory calculations, high PEC performance is ascribed to the incorporation of MoO x /MQD as hole transfer layers, retarding charge recombination, promoting hole transfer and accelerating water splitting kinetics. This proof-of-principle work not only demonstrates the potential utilization of hole transfer layers, but also sheds light on rational design and fabrication of integrated photoanodes for feasible solar energy conversion.

Quantum Dots Compete at the Acme of MXene Family for the Optimal Catalysis

“…As shown in Fig. 23c, the time-resolved [161]. Copyright @2022, Wiley-VCH photoluminescence (TRPL) spectra show that Co coupled with MQDs can increase the average carrier lifetime, indicating low carrier recombination rates, which is consistent with PL spectra result.…”

“…Copyright @2020, WILEY–VCH. f Schematic illustration of the charge transfer process for NiFeOOH/MoOx/MQD/BiVO 4 photoanodes; g Photoelectrochemical water splitting device [ 161 ]. Copyright @2022, Wiley–VCH …”

“…23 f), enhancing the light response range, leading to high activity and stability of PEC reaction (Fig. 23 g) [ 161 ]. Such strategy broads the high-performance full-spectrum photoelectrochemical water splitting [ 157 ].…”

Review on BiVO4-Based Photoanodes for Photoelectrochemical Water Oxidation: The Main Influencing Factors

“…(a) Schematic of the synthesis progress, (b) J - T pattern, and (c) η trans of OEC/MoO x /MQD/BiVO 4 . (a–c) Reproduced with permission from ref . Copyright 2022 John Wiley & Sons.…”

“…Engineering Mxenes as the cocatalyst is the most effective way to improve the charge transfer for photocatalysis, due to its ultrahigh electrical conductivity and surface activity sites. , MoO x /MXene hole transfer layers were grafted on a BiVO 4 array with combining OECs to boost the PEC performance of BiVO 4 , and the synthesis progress was shown in Figure a . The resulting OEC/MoO x /MXene quantum dots (MQD)/BiVO 4 exhibited a current density of 5.85 mA cm –2 and high charge transfer efficiency of 91% at 1.23 V versus RHE (Figure b,c).…”