Addition of Sodium Additives for Improved Performance of Water-Gas Shift Reaction over Ni-Based Catalysts

[Image: see text] The effect of Na loading on water-gas shift reaction (WGSR) activity of Ni@TiO(x)-XNa (X = 0, 0.5, 1, 2, and 5 wt %) catalysts has been investigated. Herein, we report sodium-modified Ni@TiO(x) catalysts (denoted as Ni@TiO(x)-XNa) derived from Ni(3)Ti(1)-layered double hydroxide (Ni(3)Ti(1)-LDH) precursor. The optimized Ni@TiO(x)-1Na catalyst exhibits enhanced catalytic performance toward WGSR at relatively low temperature and reaches an equilibrium CO conversion at 300 °C, which is much superior to those for most of the reported Ni-based catalysts. The H(2)-temperature-programmed reduction (H(2)-TPR) result demonstrates that the Ni@TiO(x)-1Na catalyst has a stronger metal–support interaction (MSI) than the sodium-free Ni@TiO(x) catalyst. The presence of stronger MSI significantly facilitates the electron transfer from TiO(x) support to the interfacial Ni atoms to modulate the electronic structure of Ni atoms (a sharp increase in Ni(δ−) species), inducing the generation of more surface sites (O(v)–Ti(3+)) accompanied by more interfacial sites (Ni(δ−)–O(v)–Ti(3+)), revealed by X-ray photoelectron spectroscopy (XPS). The Ni(δ−)–O(v)–Ti(3+) interfacial sites serve as dual-active sites for WGSR. The increase in the dual-active sites accounts for improvement in the catalytic performance of WGSR. With the tunable Ni–TiO(x) interaction, a feasible strategy in creating active sites by adding low-cost sodium addictive has been developed.