Ni-B coupled with borate-intercalated Ni(OH)2 for efficient and stable electrocatalytic and photocatalytic hydrogen evolution under low alkalinity

To convert solar energy into storable chemical fuel hydrogen via water splitting, it is highly required to develop efficient, low-cost and stable HER (hydrogen evolution reaction) catalysts and systems. For practical application, the HER catalysts can work in low alkaline or neutral reaction systems. However, in these reaction systems, water dissociation into proton is a rate-determining step, which can be overcome by loading metal oxide or hydroxides onto the HER catalysts. Ni(OH)(2) is a well-reported cocatalyst to assist water dissociation. Herein, NiB@Ni(OH)(2) [Ni-B with loaded Ni(OH)(2)] as a HER catalyst at weak alkalinity has been investigated. Very interestingly, we find that when borate is added into the above reaction systems, the resultant catalyst Ni-B@Ni (OH)(2)-BI shows much better HER activity and stability than Ni-B@Ni(OH)(2). The reason is that borate ions can intercalate into Ni(OH)(2) interlayers, which increases proton transport ability and stability of Ni(OH)(2) loaded on Ni-B. These findings provide new insights for design new composite catalysts of HER in low alkaline reaction systems.