Potential of solar thermochemical water-splitting cycles: A review

•Solar thermochemical cycles are promising technology to produce green hydrogen and CO.•Thermochemical oxygen pumping method have potential to become economically viable solution to remove oxygen from reduction chamber.•Solid-solid heat exchange is still a challenging process for heat recovery in solar thermochemical cycles.•Middle East and North African region (MENA region) is more suitable for industrial scale solar thermochemical plants for hydrogen and CO production.•Recent advancements in the solar thermochemical cycles are giving a hope that hydrogen production cost of 1$ per kg is possible.