The integration of electrochemical CO₂ reduction (CO₂RR) and photoelectrochemical water oxidation offers a sustainable access to valuable chemicals and fuels. Here, we develop a rapidly annealed hematite photoanode with a photocurrent density of 2.83 mA cm⁻² at 1.7 V_RHE to drive the full-reaction. We also present Cu-alloys electrocatalysis extended from CuInSnS₄, which are superior in both activity and selectivity for CO₂RR. Specifically, the screened CuInSn achieves a CO₂ to HCOOH Faradaic efficiency of 93% at a cell voltage of −2.0 V by assembling into artificial photosynthesis cell. The stability test of IT exhibits less than 3% degradation over 24 h. Furthermore, in-situ Raman spectroscopy reveals that both ${\text{CO}}_{\text{3}}^{\text{2-}}$ and CO₂ are involved in CO₂RR as reactants. The preferential affinity of C for H in the *HCO₂ intermediate enables an improved HCOOH-selectivity, highlighting the role of multifunctional Cu in reducing the cell voltage and enhancing the photocurrent density.

_{电化学 CO 2}还原 (CO ₂ RR) 和光电化学水氧化的整合提供了对有价值的化学品和燃料的可持续获取。在这里，我们开发了一种快速退火的赤铁矿光电阳极，在 1.7 V _RHE下光电流密度为 2.83 mA cm ^-2以驱动全反应。我们还展示了从 CuInSnS _{4扩展而来的铜合金电催化，它在 CO 2} RR的活性和选择性方面都非常出色。具体而言，经过筛选的 CuInSn 实现了 CO ₂通过组装到人工光合作用电池中，在-2.0 V 的电池电压下，HCOOH 的法拉第效率为 93%。IT 的稳定性测试显示 24 小时内的降解小于 3%。此外，原位拉曼光谱表明，两者${\text{一氧化碳}}_{\text{3个}}^{\text{2-}}$和CO ₂作为反应物参与CO ₂ RR。_{*HCO 2}中间体中 C 对 H 的优先亲和力提高了 HCOOH 选择性，突出了多功能 Cu 在降低电池电压和提高光电流密度方面的作用。