An　artificial　photosynthetic　(APS)　system　consisting　of　a　photoanodic　semiconductor　that　harvests　solar　photons　to　split　H2O,　a　Ni-SNG　cathodic　catalyst　for　the　dark　reaction　of　CO2　reduction　in　a　CO2-saturated　NaHCO3　solution,　and　a　proton-conducting　membrane　enabled　syngas　production　from　CO2　and　H2O　with　solar-to-syngas　energy-conversion　efficiency　of　up　to　13.6　%.　The　syngas　CO/H2　ratio　was　tunable　between　1:2　and　5:1.　Integration　of　the　APS　system　with　photovoltaic　cells　led　to　an　impressive　overall　quantum　efficiency　of　6.29　%　for　syngas　production.　The　largest　turnover　frequency　of　529.5　h−1　was　recorded　with　a　photoanodic　N-TiO2　nanorod　array　for　highly　stable　CO　production.　The　CO-evolution　rate　reached　a　maximum　of　154.9　mmol　g−1　h−1　in　the　dark　compartment　of　the　APS　cell.　Scanning　electrochemical–atomic　force　microscopy　showed　the　localization　of　electrons　on　the　single-nickel-atom　sites　of　the　Ni-SNG　catalyst,　thus　confirming　that　the　multielectron　reduction　of　CO2　to　CO　was　kinetically　favored.　©　2019　Wiley-VCH　Verlag　GmbH　&　Co.　KGaA,　Weinheim