Artificial photosynthesis in carbon dioxide (CO₂) conversion into value-added chemicals attracts considerable attention but suffers from the low activity induced by sluggish separation of photogenerated carriers and the kinetic bottleneck-induced unsatisfied selectivity. Herein, we prepare a new-style Bi/TiO₂ catalyst formed by pinning bismuth clusters on TiO₂ nanowires through being confined by pores, which exhibits high activity and selectivity towards photocatalytic production of CH₄ from CO₂. Boosted charge transfer from TiO₂ through Bi to the reactants is revealed via in situ X-ray photon spectroscopy and time-resolved photoluminescence (PL). Further, in situ Fourier transform infrared results confirm that Bi/TiO₂ not only overcomes the multi-electron kinetics challenge of CO₂ to CH₄ via boosting charge transfer, but also facilitates proton production and transfer as well as the intermediates *CHO and *CH₃O generation, ultimately achieving the tandem catalysis towards methanation. Theoretical calculation also underlies that the more favorable reaction step from *CO to *CHO on Bi/TiO₂ results in CH₄ production with higher selectivity. Our work brings new insights into rational design of photocatalysts with high performance and the formation mechanism of CO₂ to CH₄ for solar energy storage in future.

Mg₃Sb₂ has attracted intensive attention as a typical Zintl-type thermoelectric material. Despite the exceptional thermoelectric performance in n-type Mg₃Sb₂, the dimensionless figure of merit (zT) of p-type Mg₃Sb₂ remains lower than 1, which is mainly attributed to its inferior electrical properties. Herein, we synergistically optimize the thermoelectric properties of p-type Mg₃Sb₂ materials via codoping of Cd and Ag, which were synthesized by high-energy ball milling combined with hot pressing. It is found that Cd doping not only increases the carrier mobility of p-type Mg₃Sb₂, but also diminishes its thermal conductivity (κ_tot), with Mg_2.85Cd_0.5Sb₂ achieving a low κ_tot value of ~0.67 W m⁻¹ K⁻¹ at room temperature. Further Ag doping elevates the carrier concentration, so that the power factor is optimized over the entire temperature range. Eventually, a peak zT of ~0.75 at 773 K and an excellent average zT of ~0.41 over 300 − 773 K are obtained in Mg_2.82Ag_0.03Cd_0.5Sb₂, which are ~240% and ~490% higher than those of pristine Mg_3.4Sb₂, respectively. This study provides an effective pathway to synergistically improve the thermoelectric performance of p-type Mg₃Sb₂ by codoping Cd and Ag, which is beneficial to the future applications of Mg₃Sb₂-based thermoelectric materials.