Shallow resources are becoming increasingly depleted, deep resource exploration has become a global strategy. The design and testing of deep in-situ core samples are prerequisites for exploring deep resources; however, no in-situ condition-preserved coring and testing techniques and tools have been reported yet. Here, the first deep in-situ condition-preserved coring system (with the preservation of pressure, temperature, substance, light, and moisture) was developed that considers the effects of high water pressure and formation dynamic loads, along with an in-situ condition-preserved testing system. A pressure-preserved controller was designed, achieving the ultimate capacity of 140 MPa and 150 ℃. A temperature-preserved coring system combining active heating and passive insulation was constructed, realizing temperature preservation from room temperature to 150 ℃. Three generations of film-formation principles and methods were designed, achieving an excellent quality preserved rate, moisture preserved rate, and visible light barrier rate. Moreover, a deep in-situ condition-preserved coring system, and a simulated coring platform for large cores under in-situ environments was fabricated. A non-contact testing system was derived to cut and prepare specimens under in-situ environment and to perform non-contact non-destructive testing and true triaxial testing. The research findings can be successfully applied to deep coal and gas development, deep oil and gas resources assessment, and deep-sea sediment prospecting, achieving excellent application outcomes. This study provides important theoretical, technical and hardware support for deep in-situ rock physics and mechanics research and deep resource exploitation.

Significant potential exists for mining hot dry rock in coastal areas, oceans, islands, and reefs by utilizing abundant seawater as a heat-exchanging medium. It is crucial for optimizing reservoir stimulation technology to explore mechanical characteristics and mechanisms for damage of reservoir rocks during seawater mining of hot dry rock. In this research,granite was subjected to several heat treatment temperatures (100 to 500 ℃) and various numbers of fatigue thermal shocks (0-20) using seawater before Brazilian splitting tests and acoustic emission testing. The findings show that temperature, the thermal shocks, and seawater dissolution are the main factors influencing granite’s tensile strength.The temperature threshold for significant degradation of tensile strength, resulting from thermal shock from seawater and heat treatment, ranges from 200 to 300 ℃. At high temperatures (300 to 500 ℃), seawater decreases the tensile strength of granite by approximately 1.67 times compared to freshwater in cycles 0-10, and by about 3.20 times in cycles 10-20. In general, the higher the temperature and frequency of seawater impact, the greater the plasticity of the rock, the lower the tensile strength, and the higher the cumulative count and energy of acoustic emission. The number of seawater thermal shocks and granite’s tensile strength have a negative link that is substantially amplified by the temperature. The double effects of seawater cold cycle and heat treatment temperature cause granite to become more porous and progressively shift from tensile to shear damage. These results provide a benchmark for utilizing seawater as a thermogenic medium in enhanced geothermal systems for mineral extraction procedures.

The development of noble-metal-free electrocatalysts for water splitting is indispensable for the efficient production of hydrogen fuel. Herein, a Co-doped Ni-Mo phosphide nanorod arrays fabricated on porous Ni foam was shown to be an efficient binder-free electrocatalyst for water splitting. This catalyst featured exceptional activity, exhibiting an overpotential of 29 mV at a current density of 10 mA·cm^-2 for the hydrogen evolution reaction, whereas the corresponding precatalyst exhibited an overpotential of 314 mV at a current density of 50 mA·cm^-2 for the oxygen evolution reaction. The achieved electrocatalytic performance provided access to a simple water splitting system, affording a current density of 10 mA·cm^-2 at 1.47 V in 1 M KOH electrolyte. Density functional theory results indicated that Co doping and phosphorization were responsible for the high electrocatalytic performance. Thus, this work paves the way for the development of novel noble-metal-free electrocatalysts for practical H₂ production via water splitting.