Water electrolysis for hydrogen production is very important but not efficient due to high cost of the noble metal containing catalysts or low performance of the non noble metal based catalysts. Water electrolysis involves hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). HER catalysts are normally good only in acid and OER catalysts only in base, but none of them are good in both acid and base or bifunctional for both HER and OER, which makes the overall water electrolysis not efficient. We recently discovered some catalysts better than the noble metal containing ones in both acid and base, which made the overall water electrolysis more efficient than the noble metal containing catalysts. In this talk, I will present a few examples on our recent discovery on new catalysts to achieve water splitting for current density larger than 500 mA/cm2 at less than 1.7 V.