Tailored D-π Conjugation Boosts Piezocatalytic CO₂ Reduction in a Platinum(II)-Acetylide Framework

Piezocatalytic CO₂ reduction offers a sustainable route for converting mechanical energy into chemical fuels. However, its practical implementation demands catalysts that concurrently exhibit a strong piezoelectric response and high catalytic activity. Herein, we report a one-pot synthesis of well-defined metal-acetylide frameworks (TTED-M-AFs; M = Pt, Pd, Ni) incorporating M^II(PEt₃)₂ units into an extended graphdiyne-type scaffold via robust ─C≡C─M^II(PEt₃)₂─C≡C─ linkages. These molecular metal-bis(acetylide) motifs function as intrinsic active sites for CO₂ reduction. Under mechanical agitation, the Pt^II-based framework achieves a CO production rate of 72.03 µmol g^-1 h^-1 with 92.4% selectivity, outperforming its Pd^II and Ni^II analogues by factors of 1.17 and 1.73, respectively-a trend consistent with their piezoelectric coefficients (d₃₃ = 35, 21.9, and 12.5 pm V^-1). Combined experimental and theoretical analyses reveal that the piezoelectric field in TTED-Pt-AF enhances CO₂ adsorption and promotes local electron accumulation, thereby lowering the activation energy barrier. Furthermore, in situ high-pressure FT-IR spectroscopy demonstrates that the Pt^II-bis(acetylide) centers exhibit superior electronic synergy with the tetraphenylene-derived π-conjugated matrix under mechanical stress, inducing pronounced d-π orbital hybridization. The exceptional piezocatalytic performance, coupled with a scalable synthesis, underscores the promise of metal-acetylide frameworks as efficient platforms for mechano-driven CO₂ valorization.