Aging Ni(OH)2 on 3C-SiC Photoanodes to Achieve a High Photovoltage of 1.1 V and Enhanced Stability for Solar Water Splitting in Strongly Alkaline Solutions

Insight into Ni-Based Catalytic Interfaces Empowered by the Magnetic-Induced Heating Effect toward Boosting the Oxygen Evolution Reaction

The activity enhancement of magnetic catalysts toward the oxygen evolution reaction (OER) under the action of alternating magnetic fields (AMF) has attracted extensive attention. However, the magnetic-induced heating (MIH) effects of the catalysts and the current collectors are often intertwined, leading to significant controversy, as it is impossible to ascertain the true contribution of the MIH effect of the catalysts. To solve this issue and efficiently apply the MIH effect, we have developed a revised three-electrode configuration free from magnetothermal effect interference to ensure that the MIH effect in the testing system originates solely from the catalysts and designed Ni@Ni(OH)2 and Ni@Ni2P core-shell interfacial heterostructures that can rapidly and fully respond to the heat generated from the ferromagnetic Ni cores. The more representative Ni@Ni(OH)2 with a robust stability over 10 h exhibits an OER overpotential of 384 mV at 50 mA cm-2 in a 60 mT AMF, achieving an overpotential reduction of 178 mV that is double that achieved by the traditional industrial operating temperature of 80 °C. Additionally, the catalytic performance can dynamically and instantaneously respond at a second-level speed with the rapid fluctuations of the AMF intensities, presenting important potentials in the application scenarios under variable and critical working conditions.

Silicon Carbide Photonic Crystal Photoelectrode

The immense challenge of large-scale implementation of photoelectrochemical (PEC) water splitting and carbon fixation lies in the need for a cheap, durable, and efficacious photocatalyst. Cubic silicon carbide (3C-SiC) holds compelling potential due to its auspicious band positions and high-volume, high-quality, single crystal industrial manufacturing, but is hindered by its inferior light absorptivity and anodic instability. A slanted parabolic pore photonic crystal (spbPore PC) architecture with graphitic carbon nitride (g-CN), nickel(II) oxide (NiO), or 6H silicon carbide protective coatings is proposed to overcome the drawbacks of 3C-SiC photoelectrodes. A 30 µm- and 62 µm-thick 3C-SiC spbPore PC of lattice constant 0.8 µm demonstrates maximum achievable photocurrent density (MAPD) of 9.95 and 11.53 mA cm-2 in the [280.5, 600] nm region, respectively, representing 75.7% and 87.7% of the total available solar photocurrent density in this spectral range. A 50 nm-thick g-CN or NiO coating forms type-II heterojunctions with the 3C-SiC spbPore PC, facilitating the charge transport and enhancing the corrosion resistivity, all together demonstrating the MAPD of 9.81 and 10.06 mA cm-2, respectively, for 30 µm-thick PC. The scheme advances the low-cost, sustainable, real-world deployment of PEC cells for green solar fuel production.

Manipulating Electron Structure through Dual-Interface Engineering of 3C-SiC Photoanode for Enhanced Solar Water Splitting

Interface engineering is crucial for enhancing the efficiency of semiconductor-based solar energy devices. In this work, we report a novel dual-interface engineering strategy by designing a Ni(OH)2/Co3O4/3C-SiC photoanode that achieves remarkable enhancements in photoelectrochemical (PEC) water splitting performance. The optimized photoanode delivers a photocurrent density of 1.68 mA cm-2 at 1.23 V vs the reversible hydrogen electrode (RHE), representing an 8-fold increase compared to pristine 3C-SiC, along with excellent operational stability. In this architecture, Co3O4 serves as a highly efficient hole-extraction layer and forms a p-n junction with 3C-SiC, enhancing the separation of photogenerated electron-hole pairs. At the Ni(OH)2/Co3O4 interface, the formation of Ni-O-Co bonds facilitates rapid charge transfer and accelerates oxygen evolution reaction (OER) kinetics. The microwave photoconductivity decay (μ-PCD) measurements confirm a prolonged minority carrier lifetime, demonstrating the critical role of electronic structure modulation in improving charge separation and reducing recombination. Using advanced synchrotron radiation and X-ray absorption spectroscopy, we unveil critical modifications to the interfacial electronic structure induced by the dual-interface engineering and their roles in enhancing PEC performance. These findings establish a clear relationship between electronic structure modulation, charge carrier dynamics, and PEC performance, providing new insights into interface design strategies for highly efficient solar-driven water splitting systems.