The photoelectrochemical performance of Si photoanode with a metal–insulator–semiconductor (MIS) structure is limited by weak Schottky barrier and poor charge transfer. In this work, a MIS structure, n-Si|dispersed NiSi x /NiO x patches|Au nanoparticles, is designed for efficient water oxidization with high stability. The photoanode exhibits a high activity with a low onset potential of ∼0.88 V and a high photocurrent density of ∼34 mA/cm2 at 1.23 V versus reversible hydrogen electrode (RHE), and retains excellent stability in 1.0 M NaOH for ∼10 h. We find that the improved photovoltage is contributed by the strengthened pinch-off effect of inhomogeneous Schottky barriers induced by the synergistic effect of decreased Schottky barrier height difference and increased depletion width in n-Si. We show that the enhanced photocurrent attributes to the reduced hole transport resistance by introducing high-conductive NiSi x and Au-NP bridge layers. Our findings demonstrate a promising strategy for the development of highly efficient and stable Si-based photoelectrodes for water oxidization.

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Promoting the separation of photo-generated carriers is significantly important to improve the efficiency of photocatalytic hydrogen production. Therefore, we prepared g-C 3 N 4 /CeCO 3 OH/ CeO 2 (CeCeCN) ternary nanocomposite via an easy synthetic way using g-C 3 N 4 and CeO 2 as reactants. A CeCO 3 OH layer was formed and resulted in the novel ternary photocatalyst. The CeCeCN composite shows superior photocatalytic (PC) H 2 generation performance in sunlight excitation. The H 2 evolution rate is about 764 μmol h À 1 g À 1 , which is over 11 times larger than those of g-C 3 N 4 and CeO 2 . Compared with g-C 3 N 4 and CeO 2 , CeCeCN further shows a larger photo-response current density and a lower charge-transfer resistance. The remarkably increased photocatalytic property of CeCeCN is because of the efficient charge migration induced by the formed heterojunction. Our findings demonstrate that building multi-heterostructures can liberate more excited electrons for efficient hydrogen production under sunlight.

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