Piezoelectrically Enhanced Charge Carriers Transfer in a Highly Conjugated Nickel(II)-Acetylide Framework for...

The piezoelectric field within two-dimensional (2D) piezo-photocatalysts offers a promising strategy for enhancing charge carrier kinetics to convert CO₂ into valuable chemicals. However, the diversity of available 2D piezo-photocatalysts remains limited. Here, we present a highly conjugated Ni^II-acetylide framework (HETP-Ni-GY) featuring triangular atomic pores arranged in a hexagonal symmetry, constructed by incorporating Ni^II-complex into the graphdiyne (GDY) framework via Ni^II-bis(acetylide) linkages (-C≡C-Ni(PEt₃)₂-C≡C-). The triangular topology induces a densely packed yet ordered π-structure that facilitates efficient electron transfer. The synergistic interplay of light and piezoelectric field in the HETP-Ni-GY/triethanolamine (TEOA) catalytic system enables the efficient production of CO (129.80 μmol g^-1 h^-1) and CH₄ (10.08 μmol g^-1 h^-1), with a total selectivity of 78.44%. Experimental and theoretical studies reveal that the Ni^II-(PEt₃)₂ units within the framework significantly enhance piezoelectric polarization (e₁₁ = 2.46 × 10^-10 C m^-2, d₃₃ = 4.91 pm V^-1) due to increased structural distortion and noncentrosymmetry, facilitating the conversion of CO₂. The triphenylene π-columns function as electron reservoirs, while Ni^II-bis(acetylide) blocks serve as CO₂ capture and activation centers through π-d-π interactions. This study provides fundamental insights into the functionality of low-cost metal-acetylide frameworks and offers guidance for the rational design of efficient 2D piezocatalysts.