Composition‐Tuned Piezoelectricity Governs Hydrogen Evolution in Ba _1‐ <i> _x </i> Sr <i> _x </i> TiO ₃ (0 ≤ <i>x</i> ≤ 0.3)

Abstract Piezocatalysis is an innovative, clean catalytic technology. The efficiency requires enhancement due to the low level of piezoelectricity, low carrier concentration, and rapid recombination rates of the materials. Composition modulation is a critical strategy for enhancing the piezoelectric activity of ferroelectric materials. In this work, the influence of composition changes on the piezocatalytic performance of barium strontium titanate (Ba 1‐ x Sr x TiO 3 (0 ≤ x ≤ 0.3)) with varying Ba/Sr molar ratios is investigated. As the Sr content ( x ) increases from x = 0 to x = 0.3, the effective piezoelectric coefficient exhibits a significant enhancement from d eff = 46.8 pm·V −1 to d eff = 205.6 pm·V −1 , leading to an increase in the carrier concentration increase ( ΔN d ), due to the application of vibrations from ΔN d = 0.11 × 10 20 cm −3 (for x = 0) to ΔN d = 1.69 × 10 20 cm −3 (for x = 0.3). The optimal hydrogen production for each composition occurs near, but not exceeding, its Curie point ( T C） . The optimized piezocatalytic hydrogen production (per unit power) of Ba 0.7 Sr 0.3 TiO 3 at room temperature is 53.4 µmol·g −1 ·h −1 ·W −1 , which is one of the highest reported values to date. This work investigates the fundamental reasons behind composition modulation of piezocatalysis, providing constructive guidance for designing optimized piezocatalysts.