Higher polarization → stronger piezoelectric potential → drives electron–proton reduction

Conduction band minimum (CBM) must be more negative than H+/H2 potential (0 V vs NHE)

Eg ~2–3 eV ideal for efficient charge transfer

Nanorods, nanowires, porous films improve stress transfer and active surface area

Oxygen vacancies or dopants extend electron lifetime and enhance charge trapping

Piezo + co-catalyst (e.g., Pt, MoS2, CoP) lowers HER overpotential

Higher σ → more surface potential to reduce protons

Functionalized surfaces (–OH, –NH2) promote water adsorption and H+ availability

Balance between retaining tribo-charges and allowing transfer to catalytic sites

Mechanical stability under repeated contact for continuous H2 production

Use of conductive catalysts (e.g., Ni, CoP, MoS2) to boost HER kinetics

Combined piezoelectric dipoles + triboelectric charges + electret charges → stronger overall electric field

Heterojunctions (e.g., ZnO–TiO2, BaTiO3–graphene) suppress recombination

Conductive pathways (CNTs, graphene, metal sulfides) enable efficient electron transfer to protons

Large surface area nanostructures → more catalytic sites

Pre-stored charges provide bias field to stabilize long-term HER performance