Solar water splitting based on semiconductor photoelectrodes is a promising route to convert solar energy into renewable hydrogen fuel. Since the pioneering work of photoelectrochemical (PEC) systems in 1972, a large variety of semiconductors such as oxides, sulfides, phosphides, and silicon have been studied in the context of PEC water splitting configuration. Among them, silicon carbide (SiC) exhibits an excellent energy band structure that straddles the water redox potentials. In particular, cubic SiC (3C‐SiC), with a suitable bandgap of 2.36 eV, is favorable for visible sunlight absorption. Recently, 3C‐SiC has attracted much interest in PEC water splitting. In this review, the progress, challenges, and prospects of using SiC for PEC water splitting are summarized.

Local chemical states and thermal stabilities of N dopants in ZnO:N film are investigated by temperature-dependent x-ray photoelectron spectroscopy. Different types of N local states are detected, including ${\text{N}}_2$ molecules occupying O sites $\left[{\left({\text{N}}_2\right)}_{\text{O}}\right]$ , –NO species, substitutional N atoms in O- and N-rich local environments ($\alpha$ - and $\beta {\text{-N}}_{\text{O}}$ ). Compared to the $\beta {\text{-N}}_{\text{O}}$ , the $\alpha {\text{-N}}_{\text{O}}$ shows a better thermal stability up to 723 K. However, the transformation from $\alpha {\text{-N}}_{\text{O}}$ acceptor to undesirable ${\left({\text{N}}_2\right)}_{\text{O}}$ donor occurs above 743 K. The variation of N local states also affects Zn and O binding energies. Photoluminescence studies indicate the shallow acceptor nature of $\alpha {\text{-N}}_{\text{O}}$ .

Photoelectrochemical (PEC) water-splitting offers a promising method to convert the intermittent solar energy into renewable and storable chemical energy. However, the most studied semiconductors generally exhibit a poor PEC performance including low photocurrent, small photovoltage, and/or large onset potential. In this work, we demonstrate a significant enhancement of photovoltage and photocurrent together with a substantial decrease of onset potential by introducing electrocatalytic and p-type NiO nanoclusters on an n-type cubic silicon carbide (3C-SiC) photoanode. Under AM1.5G 100 mW cm⁻² illumination, the NiO-coated 3C-SiC photoanode exhibits a photocurrent density of 1.01 mA cm⁻² at 0.55 V versus reversible hydrogen electrode (V_RHE), a very low onset potential of 0.20 V_RHE and a high fill factor of 57% for PEC water splitting. Moreover, the 3C-SiC/NiO photoanode shows a high photovoltage of 1.0 V, which is the highest value among reported photovoltages. The faradaic efficiency measurements demonstrate that NiO also protects the 3C-SiC surface against photo-corrosion. The impedance measurements evidence that the 3C-SiC/NiO photoanode facilitates the charge transfer for water oxidation. The valence-band position measurements confirm the formation of the 3C-SiC/NiO p–n heterojunction, which promotes the separation of the photogenerated carriers and reduces carrier recombination, thus resulting in enhanced solar water-splitting.