Semiconductor　quantum　wells　(QWs)　exhibit　high　charge-utilization　efficiency　for　light-emitting　applications　due　to　their　strong　charge　confinement　effect.　Inspired　by　this　effect,　herein,　this　work　proposes　a　new　idea　to　significantly　improve　the　photo-generated　charge　separation　for　attaining　a　highly-efficient　solar-to-fuels　conversion　process　through　＂semi-reversing＂　the　conventional　QWs　to　confine　only　the　photo-generated　electrons.　This　electron　confinement-improved　charge　separation　is　implemented　in　the　well-designed　model　of　the　CdS/TiO2/CdS　semi-reversed　QW　(SRQW)　structure.　The　latter　is　fabricated　by　selectively　assembling　CdS　quantum　dots　(QDs)　onto　the　{101}　facets　(ultra-thin　edge　regions)　of　the　TiO2　nanosheets　(NSs).　Upon　light　excitation,　the　photo-generated　electrons　of　SRQW　can　be　confined　on　the　TiO2-{101}　facets　in　the　vicinity　of　the　CdS/TiO2　hetero-interface.　Thereby,　the　continuous　multi-electron　injection　to　the　adsorbed　reactants　on　the　interfacial　active-sites　is　significantly　accelerated.　Thus,　the　CdS/TiO2/CdS　SRQW　exhibits　approximate　to　35.7　and　approximate　to　56.0-fold　enhancements　on　the　photocatalytic　activities　for　water　and　CO2　reduction,　respectively,　compared　to　those　of　pure　TiO2.　Correspondingly,　its　CH4-product　selectivity　is　increased　by　approximate　to　180%.　This　work　provides　a　novel　charge　separation　mechanism,　which　is　of　great　importance　for　the　design　of　the　next-generation　quantum-sized　photocatalysts　for　solar-to-fuels　conversion.