Abstract:　Sunlight　is　the　most　abundant　and　inexhaustible　energy　source　on　earth.　However,　its　low　energy　density,　dispersibility　and　intermittent　nature　make　its　direct　utilization　with　industrial　relevance　challenging,　suggesting　that　converting　sunlight　into　chemical　energy　and　storing　it　is　a　valuable　measure　to　achieve　global　sustainable　development.　Carbon–neutral,　clean　and　secondary　pollution-free　solar-driven　water　splitting　to　produce　hydrogen　is　one　of　the　most　attractive　avenues　among　all　the　current　options　and　is　expected　to　realize　the　transformation　from　dependence　on　fossil　fuels　to　zero-pollution　hydrogen.　Artificial　photosynthetic　systems　(APSs)　based　on　photoelectrochemical　(PEC)　devices　appear　to　be　an　ideal　avenue　to　efficiently　achieve　solar-to-hydrogen　conversion.　In　this　review,　we　comprehensively　highlight　the　recent　developments　in　photocathodes,　including　architectures,　semiconductor　photoabsorbers　and　performance　optimization　strategies.　In　particular,　frontier　research　cases　of　organic　semiconductors,　dye　sensitization　and　surface　grafted　molecular　catalysts　applied　to　APSs　based　on　frontier　(molecular)　orbital　theory　and　semiconductor　energy　band　theory　are　discussed.　Moreover,　research　advances　in　typical　photoelectrodes　with　the　metal–insulator–semiconductor　(MIS)　architecture　based　on　quantum　tunnelling　are　also　introduced.　Finally,　we　discuss　the　benchmarks　and　protocols　for　designing　integrated　tandem　photoelectrodes　and　PEC　systems　that　conform　to　the　solar　spectrum　to　achieve　high-efficiency　and　cost-effective　solar-to-hydrogen　conversion　at　an　industrial　scale　in　the　near　future.　Graphical　abstract:　[Figure　not　available:　see　fulltext.]　©　2023,　Shanghai　University　and　Periodicals　Agency　of　Shanghai　University.