2D tremella-like Co6Al2CO3(OH)16•4H2O in-situ growing on 1D rod-shape ZnFe2O4 to accelerate the surface reaction kinetics for photoelectrochemical water splitting

Abstract

ZnFe2O4 films applied for photoelectrochemical (PEC) water splitting is still confronted with some challenges like long distance of charge transfer and slow surface reaction kinetics. Herein, ZnFe2O4 films are initially modified by controlling morphology via regulating iron source during the hydrothermal process. A series of measurements demonstrate that one-dimensional (1D) rod-like ZnFe2O4 films possess a better PEC performance (0.11 mA cm−2 at 1.23 V vs. RHE) than that of petal-like ZnFe2O4 films (0.07 mA cm−2 at 1.23 V vs. RHE). Furthermore, the slow surface reaction kinetics of ZnFe2O4 nanorods (NRs) is accelerated by in-situ growing two-dimensional (2D) tremella-like layered double hydroxide Co6Al2CO3(OH)16•4H2O (denoted as CoAl-LDH) through a fugacious hydrothermal method. The photocurrent density of ZnFe2O4/CoAl-LDH is 0.60 mA cm−2 at 1.23 V vs. RHE, which is 5.45 times than that of ZnFe2O4 NRs. Notably, the onset potential of ZnFe2O4/CoAl-LDH is left shifted about 0.19 V–0.77 V vs. RHE compared with ZnFe2O4 NRs (0.96 V vs. RHE). This is ascribed to Co species providing active sites to capture holes for water oxidation reaction and Al species offering the support for layer skeleton. This is a first exemplification of optimizing ZnFe2O4 films for PEC water splitting through tuning morphology and depositing layered double hydroxides, it is meaningful to perceive and conceive efficient PEC devices in the future.