## 1 Introduction
The catalytic  
Figure 1: Principal scheme of electrochemical hydrogen pump/compressor (EHP/C) in a single cell mode. layers, where electrochemical hydrogen oxidation (HOR) and reduction (HRR) occur, must facilitate the transport of protons, electrons, and gaseous reactants while simultaneously minimizing the activation energy required for the reactions at both the anode and cathode, as illustrated in Figure 2. Achieving an optimal balance in catalyst loading is vital to enhance the overall efficiency and performance of the EHP/C system [27]. Platinum (Pt) and palladium (Pd) nanoparticles are widely recognized for their exceptional catalytic activity in electrochemical hydrogen compression (EHP/C) and have been extensively studied in the literature [27; 28; 29; 30]. However, a significant drawback of Pt and Pd nanoparticles is their tendency to agglomerate during the electrochemical reactions, particularly under high pressure [31; 32]. This leads to a reduction in the active surface area of the catalysts, thereby decreasing catalyst utilization. To mitigate this issue, various catalytic support materials are employed to stabilize the catalyst nanoparticles and maintain their dispersion over the support [33; 34]. The selection of appropriate support is critical for the performance of EHP/C systems. Key parameters influencing this choice include high electrical conductivity, large specific surface area, and optimized water management [35]. These characteristics are critical to maintaining the structural integrity and catalytic activity of the catalyst over prolonged operation. Strong metal-support interactions (SMSIs) play a crucial role in enhancing the stability, efficiency, and overall performance of metal-based catalysts in hydrogen energy converter devices. One of the primary benefits of SMSIs is the prevention of nanoparticle agglomeration [36; 37; 38; 39; 40]. In EHP/C applications, the interaction between metal catalysts and the support material strengthens the adhesion of nanoparticles, minimizing their mobility under the high pressures, elevated temperatures, and fluctuating operational conditions typical of hydrogen compression. This stabilization improves catalyst durability and maintains activity, addressing a key challenge associated with conventional carbon-supported catalysts, which often suffer from sintering-induced deactivation [41]. Beyond enhancing structural integrity, strong metal-support interactions (SMSIs) also increase the density of catalytically active sites at the metal-support interface. By promoting better metal dispersion and electronic communication with the support, SMSIs facilitate more efficient electrochemical processes. The optimized spatial and electronic distributions of the active sites accelerate the reaction kinetics, thereby improving hydrogen compression efficiency and enabling effective energy conversion in EHP/C systems [42; 43]. In particular, Pt-O-Ti bonding exemplifies a tailored form of SMSIs that significantly enhances the metal-carrier electron interaction. This specific interfacial linkage plays a key role in modulating the electronic density of Pt, as the formation of Pt-O-Ti bonds leads to charge redistribution within the Pt nanoparticles. Such redistribution finely tunes the binding energy of reaction intermediates, optimizing catalytic performance. Addition  
Figure 2: Principal scheme of nanosized, Pt-based catalysts dispersed over the catalytic support. ally, this interfacial architecture stabilizes Pt against agglomeration and leaching under corrosive, acidic conditions while simultaneously enhancing its intrinsic catalytic activity. Consequently, interface engineering through Pt-O-Ti bonding presents a robust strategy for the development of high-performance and durable electrodes for hydrogen-related electrochemical technologies [44].