Robust route to HO and H via intermediate water splitting enabled by capitalizing on minimum vanadium-doped piezocatalysts.

UNLABELLED

HO is an environmentally friendly chemical for a wide range of water treatments. The industrial production of HO is an anthraquinone oxidation process, which, however, consumes extensive energy and produces pollution. Here we report a green and sustainable piezocatalytic intermediate water splitting process to simultaneously obtain HO and H using single crystal vanadium (V)-doped NaNbO (V-NaNbO) nanocubes as catalysts. The introduction of V improves the specific surface area and active sites of NaNbO. Notably, V-NaNbO piezocatalysts of 10 mg exhibit 3.1-fold higher piezocatalytic efficiency than the same catalysts of 50 mg, as more piezocatalysts lead to higher probability of aggregation. The aggregation causes reducing active sites and decreased built-in electric field due to the neutralization between different nano-catalysts. Remarkably, piezocatalytic HO and H production rates of V-NaNbO (10 mol%) nanocubes (102.6 and 346.2 µmol·g·h, respectively) are increased by 2.2 and 4.6 times compared to the as-prepared pristine NaNbO counterparts, respectively. This improved catalytic efficiency is attributed to the promoted piezo-response and more active sites of NaNbO catalysts after V doping, as uncovered by piezo-response force microscopy (PFM) and density functional theory (DFT) simulation. More importantly, our DFT results illustrate that inducing V could reduce the dynamic barrier of water dissociation over NaNbO, thus enhancing the yield of HO and H. This facile yet robust piezocatalytic route using minimal amounts of catalysts to obtain HO and H may stand out as a promising candidate for environmental applications and water splitting.

ELECTRONIC SUPPLEMENTARY MATERIAL

Supplementary material (typical Raman spectra of NaNbO and V-NaNbO with various doping concentrations (Fig. S1). XPS spectra of Na 1s (Fig. S2). PL spectra of solution obtained from the piezocatalytic system using NaNbO and V-NaNbO (10 mol%) as the catalysts after 1 h (Fig. S3). The length of NaNbO and V-NaNbO nanocubes calculated from XRD data of their (101) planes (Table S1)) is available in the online version of this article at 10.1007/s12274-022-4506-0.