Density functional theory (DFT) calculations may provide valuable insights into the underlying reasons for the high stability and catalytic activity of [Pt17(CO)12(PPh3)8] z . Such study could also help predict the geometric and electronic structures of other potentially stable Ptn(CO)m(PR3)l NCs that could be synthesized in the future. With ongoing depletion of fossil resources and global warming, the transition to a hydrogen (H2)-based energy economy is increasingly necessary. Currently, H2 is predominantly produced from methane derived from natural gas and coal, which are fossil fuels. Thus, to reduce its environmental impact, water electrolysis using electricity supplied by renewable energy sources has gained significant attention as a method for H2 production (Fig. ). Water electrolysis involves both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), where H2 is generated through the reduction of water in the HER. Among the various water electrolysis systems, proton exchange membrane water electrolyzers (PEMWEs) are particularly attractive owing to their compact size, high energy efficiency, high H2-production rate, and quick response to voltage fluctuations. However, the widespread adoption of PEMWEs faces a major challenge: the need of stable and active electrocatalysts that can operate effectively under acidic conditions.