The efficiency and stability of narrow-gap semiconductor-based photoelectrodes are two fundamental factors for realizing their industrial solar-to-fuel conversion.

Commercial stainless steel has attracted increasing interest due to their rich content in transition metal elements and corrosion resistance properties. In this work, we design a facile and rapid route to in-situ fabricate the Cr doped FeNi layered double hydroxides nanosheets (LDHs) on modified stainless steel (Cr–FeNi LDH @ ESS) under ambient condition.The ultra small scaled 2D structure only around 20 nm diameter and metal ions with multivalent oxidation state were observed on the in situ fabricated LDHs, which provides high active area and active sites and thus promote excellent oxygen evolution reaction (OER). The Cr–FeNi LDH @ESS electrocatalysts exhibit an over potential of 280 mV at 10 mA cm⁻² and achieves a Tafel slope of 44 mV dec⁻¹ for OER in the 1.0 M KOH aqueous solution. We anticipate that the operating strategy of our system may promote the development of commercial non-precious productions as the efficient electrocatalysts for energy storage and conversion.

A direct current magnetron sputtering (DCMS) system at room temperature was applied to deposit the Ti/TiN/TiCN films. In order to research the effect of the microstructure of the TiN/TiCN layer on the Ti/TiN/TiCN films, the deposition time ratio of the TiN/TiCN layer ranged from 28.57 to 200%, and the whole deposition time of the films and the deposition time of Ti layer were constant. In this work, the relationship between structure and mechanical properties of films were investigated. The research results showed that the composition and structure of the films only slightly changed, while the crystalline orientation of the TiCN layer was of significant variation with the deposition time of the TiN layer. It is shown that the adhesion strength and internal stresses were 18.6 ± 1.5 N and 140 MPa when the deposition time ratio was 50%. By adjusting the deposition time ratio, the films displayed significant improvement in tribological behaviors. The coefficients of friction (COF) for the films deposited under deposition time ratio of 50% were about only 0.139 when the value of COF was stabilized. This work can provide a good wear-resisting film prepared approach at room temperature.

To ease the scarcity of lithium (Li) resource and cut down on environmental pollution, an efficient, selective, inexpensive and sustainable Li recycling process from waste batteries is needed, which is yet to be achieved. Here, we report a low-potential photoelectrochemical (PEC) system that selectively and efficiently extracts Li metals from multi-cation electrolytes under 1 sun illumination. Based on the difference of redox potential, we can get rid of the disturbance of other cations (i.e., Fe, Co and Ni ions) by a bias-free PEC device to realize the extraction of high-purity Li metals on a coplanar Si-based photocathode-TiO ₂ photoanode tandem device at 2 V of applied bias (far less than the redox potentials of Li ⁺ /Li). In such system, the extraction rate of Li metals (purity > 99.5%) exceeds 1.35 g h ⁻¹ m ⁻² with 90% of Faradaic efficiency. Long-term experiments, different electrode/electrolyte tests, and various price assessments further demonstrate the stability, compatibility and economy of PEC extraction system, enabling a solar-driven pathway for the recycling of critical metal resources.