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Proton exchange membrane fuel cell (PEMFC) is a potential candidate as the power source for vehicle application. However, problems related to water and thermal management must be resolved before their large-scale promotion. Numerical models are often used as powerful tools to describe the electrochemical and transport phenomena occurring in PEMFC, which are important to water and thermal management. In this study, two-phase, non-isothermal, transient models are employed to research the local dynamic characteristics inside PEMFC under road driving conditions and different operating conditions. The simulation results indicate that overload running often causes local high temperature, which can lead to membrane dehydration, voltage loss, and power overshoot as load increases. If the temperature is above the glass transition temperature of the membrane, it will even lead to membrane mechanical degradation. According to our research, controlling the operating temperature below 378 K and reducing the coolant temperature in advance are the effective ways to prevent the aforementioned attenuation.

Developing efficient and durable oxygen evolution electrocatalyst is of paramount importance for the large-scale supply of renewable energy sources. Herein, we report a design of significant surface hydrophilicity based on the cobalt oxyhydroxide (CoOOH) nanosheets to greatly improve the surface hydroxyl species adsorption and reaction kinetics at the Helmholtz double layer for high-efficiency water oxidation activity. The as-designed CoOOH-Graphene nanosheets achieve a small surface water contact angle of ~23° and a large double-layer capacitance (Cdl) of 8.44 mF/cm2, thus could evidently strengthen surface species adsorption and trigger electrochemical oxygen evolution reaction (OER) under a quite low onset potential of 200 mV with an excellent Tafel slope of 32 mV/dec. X-ray absorption spectroscopy and first-principles calculations demonstrate that the strong interface electron coupling between CoOOH and graphene extracts partial electrons from the active sties and increases the electron state density around the Fermi level, and effectively promotes the surface intermediates formation for efficient OER.

Highly efficient oxygen evolution driven by abundant sunlight is a key to realize overall water splitting for large-scale conversion of renewable energy. Here, we report a strategy for the interfacial atomic and electronic coupling of layered CoOOH and BiVO4to deactivate the surface trapping states and suppress the charge-carrier recombination for high photoelectrochemical (PEC) water oxidation activity. The successful synthesis of a 3D ultrathin-CoOOH-overlayer-coated coral-like BiVO4photoanode effectively tailors the migration route of photocarriers on the semiconductor/liquid interface to realize a great increase of ∼200% in the photovoltage relative to bare BiVO4, consequently decreasing the corresponding onset potential of PEC water splitting from 0.60 to 0.20 VRHE. As a result, the unique CoOOH/BiVO4photoanode could efficiently perform PEC water oxidation in a neutral aqueous solution (pH = 7) with a high photocurrent density of 4.0 mA/cm2at 1.23 VRHEand a prominent quantum efficiency of 65% at 450 nm. Electronic structural characterizations and theoretical calculations reveal that the combination of layered CoOOH and BiVO4forming interfacial oxo-bridge bonding could greatly eliminate surface trapping states and promote the direct transfer of photogenerated holes from the valence band to the surface water redox potential for water oxidation.

Direct water splitting in pure water relying on photocatalysis is an effective way to realize an efficient solar to chemical fuel conversion toward solving the global energy crisis and environmental problems. Here, via a “high-valence metal single-atom confinement” strategy, we effectively modify the valence band structure of the semiconductor photocatalyst toward a spontaneous photocatalytic water splitting in pure water. This as-prepared PtII–C3N4could achieve an efficient photocatalytic water splitting activity with the H2production rate up to ∼140 μmol g–1h–1, about 10 times that of Pt nanoparticle–C3N4(15 μmol g–1h–1). Moreover, the unique PtII–C3N4suspension in pure water exhibits an impressive quantum efficiency of 1.5% at 420 nm under visible light irradiation. Electronic structure characterizations and theoretical calculations reveal that the hybridization of PtII5d and N 2p obviously downward shifts the valence band maximum level of PtII–C3N4by 0.26 V relative to g-C3N4, which could significantly promote the reaction thermodynamics of oxygen evolution toward the high photocatalytic water splitting activity.

The development of organometallic complexes with abundant stable single-atom active sites is highly desirable for cost-effective and commercial electrocatalysis towards renewable energy conversion and storage. Here, we report an atomic-level design and construction of a new type of organometallic Au1Nxsingle-site confined on organic carbon-nitride support as a promising bifunctional electrocatalyst for efficient and durable oxygen reduction (ORR) and evolution reaction (OER) performance. The combination of atomic characterizations and theoretical calculations confirm that the atomically dispersed Au1+atoms are grafted onto carbon-nitride support by covalent Au–N bonds via an amine-induced-reduction strategy, forming atomic Au1Nxsingle-sites with potential oxygen-related catalytic activity. Hence, this developed Au1Nxsingle-site electrocatalyst could exhibit excellent electrocatalytic activity and durability with extraordinarily large mass activities of ~9000 A•gAu−1for ORR at the half-wave potential 0.76 V, and of ~1500 A•gAu−1for OER at overpotential 0.45 V, 20–26 times higher than those of benchmarking Pt/C and RuO2electrocatalysts.

Improving the performance of proton exchange membrane fuel cells (PEMFCs) can help accelerate their large-scale commercial application. In this paper, an agglomerate model is proposed and developed by coupling a one-dimensional local oxygen transport model with a one-dimensional multiphase non-isothermal fuel cell sub-model to study the influences of catalyst dimension parameters (Pt radius, Pt average dispersity, carbon radius) on local oxygen transport and cell performance. And this elaborate model shows that the smaller Pt radius, carbon radius, and the higher Pt average dispersity can reduce the transport distance of oxygen molecules from the pores to the active sites, and then decrease the local resistance. Based on the above understanding, the optimum performance of the optimized cell with a Pt loading of 0.2 mg cm-2is improved by 22%, slightly higher than the original cell with a Pt loading of 0.4 mg cm-2, which achieves a 50% reduction in Pt loading while maintaining the cell performance. This research will give a guide for improving cell performance.