The efficiency of proton exchange membrane water electrolysis (PEM-WE) for hydrogen production is heavily dependent on the noble metal iridium-based catalysts. However, the scarcity of iridium limits the large-scale application of PEM-WE. To address this issue, it is promising to select an appropriate support because it not only enhances the utilization efficiency of noble metals but also improve mass transport under high current. Herein, we supported amorphous IrO_x nanosheets onto the hollow TiO₂ sphere (denoted as IrO_x), which demonstrated excellent performance in acidic electrolytic water splitting. Specifically, the annealed IrO_x catalyst at 150 ^oC in air exhibited a mass activity of 1347.5 A g^-1_Ir, which is much higher than that of commercial IrO₂ of 12.33 A g^-1_Ir at the overpotential of 300 mV for oxygen evolution reaction (OER). Meanwhile, the annealed IrO_x exhibited good stability for 600 hours operating at 10mA cm^-2. Moreover, when using IrO_x and annealed IrO_x catalysts for water splitting, a cell voltage as low as 1.485 V can be achieved at 10 mA cm^-2. The cell can continuously operate for 200 hours with negligible degradation of performance.

IrRu bimetallic oxides are recognized as the promising acidic oxygen evolution reaction (OER) catalysts, but breaking the trade-off between their activity and stability is an unresolved question. Meanwhile, addressing the issues of mass transport obstruction of IrRu bimetallic oxides under high current remains a challenge for the development of proton exchange membrane water electrolysis (PEM-WE). Herein, we prepared an IrRuO_x nanomeshes (IrRuO_x NMs) with high coordination number (CN) of Ir–O–Ru bonds in a mixed molten salt with high solubility of the Ir/Ru precursor. X-ray absorption spectroscopy analysis revealed that the IrRuO_x NMs possess high coordination number of Ir–O–Ru bonds (CN_Ir–O–Ru = 5.6) with a distance of 3.18 Å. Moreover, the nanomesh structures of IrRuO_x NMs provided hierarchical channels to accelerate the transport of oxygen and water, thus further improving the electrochemical activity. Consequently, the IrRuO_x NMs as OER catalysts can simultaneously achieve high activity and stability with low overpotential of 196 mV to reach 10 mA·cm⁻² and slightly increase by 70 mV over 650 h test. Differential electrochemical mass spectrometry tests suggest that the preferred OER mechanism for IrRuO_x NMs is the adsorbent evolution mechanism, which is beneficial for the robust structural stability.

Manipulating the oxidation state of Cu catalysts can significantly affect the selectivity and activity of electrocatalytic carbon dioxide reduction (CO₂RR). However, the thermodynamically favorable cathodic reduction to metallic states typically leads to catalytic deactivation. Herein, a defect construction strategy is employed to prepare crystalline/amorphous Cu₂₊₁O/CuO_x heterostructures (c/a-CuO_x) with abundant Cu⁰ and Cu^δ+ (0 < δ < 1) sites for CO₂RR. The C₂₊ Faradaic efficiency of the heterostructured Cu catalyst is up to 81.3%, with partial current densities of 406.7 mA·cm⁻². Significantly, real-time monitoring of the Cu oxidation state evolution by in-situ Raman spectroscopy confirms the stability of Cu^δ+ species under long-term high current density operation. Density functional theory (DFT) calculations further reveal that the adjacent Cu⁰ and Cu^δ+ sites in heterostructured c/a-CuO_x can efficiently reduce the energy barrier of CO coupling for C₂₊ products.

Highly efficient and stable oxygen reduction reaction (ORR) electrocatalysts are remarkably important but challenging for advancing the large-scale commercialization of practical proton exchange membrane fuel cells (PEMFCs). In this work, we report that the introduction of interstitial hydrogen atoms into PtPd nanotubes can significantly promote ORR performance without scarifying the durability. The enhanced mass activity was 8.8 times higher than that of commercial Pt/C. The accelerated durability test showed negligible activity attenuation after 30,000 cycles. Additionally, H₂/O₂ fuel cell tests further verified the excellent activity of PtPd-H nanotubes with a maximum power density of 1.32 W·cm⁻², superior to that of commercial Pt/C (1.16 W·cm⁻²). Density functional theory calculations demonstrated the incorporation of hydrogen atoms gives rise to the broadening of Pt d-band and the downshift of d-band center, which consequently leads to the weaker intermediates binding and enhanced ORR activity.