RuO2 is the most efficient material reported so far for acidic oxygen evolution reaction (OER), yet suffering from insufficient stability in practical water-splitting operations. Targeting on this issue, herein we report an electronic structure modulating strategy by dispersing RuO2 over defective TiO2 enriched with oxygen vacancies (RuO2/D-TiO2). Synergetic (spectro-)­electrochemistry and theoretical simulations reveal a continuous band structure at the interface between RuO2 and defective TiO2, as well as a lowered energetic barrier for *OOH formation, which are accountable for the largely enhanced acidic OER kinetics. As a result, the as-prepared RuO2/D-TiO2 catalyst exhibits a low overpotential of 180 mV at 10 mA cm–2, a low cell voltage of 1.84 V at 2 A cm–2, and a long lifetime above 100 h at 200 mA cm–2, providing hints for a more robust acidic OER catalyst design.

Heterogeneous catalysis of formic acid dehydrogenation at room temperature is a promising tactic for safely storing and producing H 2 as an efficient energy carrier. Up to now, the catalysts for this purpose are largely developed based on trial and error. In this work, we demonstrate that a careful analysis of the formic acid dehydrogenation mechanism can shed light on rational design and facile synthesis of efficient Pd-based catalysts, that is, carbon black-supported fine Pd nanoparticles with adatoms of an sp metal (including but not limited to Bi). In fact, Pd@Bi/C with an optimal atomic ratio doubles the Pd mass activity of the Pd/C in terms of hydrogen production rate, specifically with a global turnover frequency of 4350 h −1 at 303 K in a mixed 1.1 M formic acid and 2.4 M sodium formate solution without engineering the catalyst support. Apparent kinetic measurement, in situ interfacial IR spectroscopy, and density functional theory calculation results further confirm that Bi adatoms favor the adsorption of the formate intermediate to facilitate the C−H bond cleavage and weaken the adsorption of H and CO on Pd sites, resulting in a prominently enhanced H 2 production performance.

The electrochemical CO2 reduction reaction (CO2RR) on Pd-based electrodes to dissolved formate and/or gaseous CO is largely dependent on potential and the electrode material, yet there is a lack of molecular-level insights into this dependence. Herein, in situ attenuated total reflection surface enhanced infrared absorption spectroscopy (ATR-SEIRAS) in conjunction with differential electrochemical mass spectrometry (DEMS), gas chromatography (GC), and nuclear magnetic resonance (NMR) measurements is applied to investigate the CO2RR on Pd and Pd-B film electrodes, providing a direct observation of the role of surface CO as well as the B-doping effect at varied potentials. Comprehensive spectrometric results reveal that at lower overpotentials, CO gradually accumulates on both Pd electrode surfaces poisoning the dominant formate pathway, while at higher overpotentials, surface CO forms facilely with linearly bonded CO (the minor surface CO species) acting as an active precursor and bridge-bonded CO (the major surface CO species) as a spectator toward the gaseous CO product. Moreover, B-doping in Pd hinders CO formation and promotes formate production on the Pd-B electrode for the CO2RR as compared to that on the pristine Pd electrode at all of the overpotentials under investigation.